Root/fs/ntfs/mft.c

1/**
2 * mft.c - NTFS kernel mft record operations. Part of the Linux-NTFS project.
3 *
4 * Copyright (c) 2001-2011 Anton Altaparmakov and Tuxera Inc.
5 * Copyright (c) 2002 Richard Russon
6 *
7 * This program/include file is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as published
9 * by the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program/include file is distributed in the hope that it will be
13 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program (in the main directory of the Linux-NTFS
19 * distribution in the file COPYING); if not, write to the Free Software
20 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 */
22
23#include <linux/buffer_head.h>
24#include <linux/slab.h>
25#include <linux/swap.h>
26
27#include "attrib.h"
28#include "aops.h"
29#include "bitmap.h"
30#include "debug.h"
31#include "dir.h"
32#include "lcnalloc.h"
33#include "malloc.h"
34#include "mft.h"
35#include "ntfs.h"
36
37/**
38 * map_mft_record_page - map the page in which a specific mft record resides
39 * @ni: ntfs inode whose mft record page to map
40 *
41 * This maps the page in which the mft record of the ntfs inode @ni is situated
42 * and returns a pointer to the mft record within the mapped page.
43 *
44 * Return value needs to be checked with IS_ERR() and if that is true PTR_ERR()
45 * contains the negative error code returned.
46 */
47static inline MFT_RECORD *map_mft_record_page(ntfs_inode *ni)
48{
49    loff_t i_size;
50    ntfs_volume *vol = ni->vol;
51    struct inode *mft_vi = vol->mft_ino;
52    struct page *page;
53    unsigned long index, end_index;
54    unsigned ofs;
55
56    BUG_ON(ni->page);
57    /*
58     * The index into the page cache and the offset within the page cache
59     * page of the wanted mft record. FIXME: We need to check for
60     * overflowing the unsigned long, but I don't think we would ever get
61     * here if the volume was that big...
62     */
63    index = (u64)ni->mft_no << vol->mft_record_size_bits >>
64            PAGE_CACHE_SHIFT;
65    ofs = (ni->mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
66
67    i_size = i_size_read(mft_vi);
68    /* The maximum valid index into the page cache for $MFT's data. */
69    end_index = i_size >> PAGE_CACHE_SHIFT;
70
71    /* If the wanted index is out of bounds the mft record doesn't exist. */
72    if (unlikely(index >= end_index)) {
73        if (index > end_index || (i_size & ~PAGE_CACHE_MASK) < ofs +
74                vol->mft_record_size) {
75            page = ERR_PTR(-ENOENT);
76            ntfs_error(vol->sb, "Attempt to read mft record 0x%lx, "
77                    "which is beyond the end of the mft. "
78                    "This is probably a bug in the ntfs "
79                    "driver.", ni->mft_no);
80            goto err_out;
81        }
82    }
83    /* Read, map, and pin the page. */
84    page = ntfs_map_page(mft_vi->i_mapping, index);
85    if (likely(!IS_ERR(page))) {
86        /* Catch multi sector transfer fixup errors. */
87        if (likely(ntfs_is_mft_recordp((le32*)(page_address(page) +
88                ofs)))) {
89            ni->page = page;
90            ni->page_ofs = ofs;
91            return page_address(page) + ofs;
92        }
93        ntfs_error(vol->sb, "Mft record 0x%lx is corrupt. "
94                "Run chkdsk.", ni->mft_no);
95        ntfs_unmap_page(page);
96        page = ERR_PTR(-EIO);
97        NVolSetErrors(vol);
98    }
99err_out:
100    ni->page = NULL;
101    ni->page_ofs = 0;
102    return (void*)page;
103}
104
105/**
106 * map_mft_record - map, pin and lock an mft record
107 * @ni: ntfs inode whose MFT record to map
108 *
109 * First, take the mrec_lock mutex. We might now be sleeping, while waiting
110 * for the mutex if it was already locked by someone else.
111 *
112 * The page of the record is mapped using map_mft_record_page() before being
113 * returned to the caller.
114 *
115 * This in turn uses ntfs_map_page() to get the page containing the wanted mft
116 * record (it in turn calls read_cache_page() which reads it in from disk if
117 * necessary, increments the use count on the page so that it cannot disappear
118 * under us and returns a reference to the page cache page).
119 *
120 * If read_cache_page() invokes ntfs_readpage() to load the page from disk, it
121 * sets PG_locked and clears PG_uptodate on the page. Once I/O has completed
122 * and the post-read mst fixups on each mft record in the page have been
123 * performed, the page gets PG_uptodate set and PG_locked cleared (this is done
124 * in our asynchronous I/O completion handler end_buffer_read_mft_async()).
125 * ntfs_map_page() waits for PG_locked to become clear and checks if
126 * PG_uptodate is set and returns an error code if not. This provides
127 * sufficient protection against races when reading/using the page.
128 *
129 * However there is the write mapping to think about. Doing the above described
130 * checking here will be fine, because when initiating the write we will set
131 * PG_locked and clear PG_uptodate making sure nobody is touching the page
132 * contents. Doing the locking this way means that the commit to disk code in
133 * the page cache code paths is automatically sufficiently locked with us as
134 * we will not touch a page that has been locked or is not uptodate. The only
135 * locking problem then is them locking the page while we are accessing it.
136 *
137 * So that code will end up having to own the mrec_lock of all mft
138 * records/inodes present in the page before I/O can proceed. In that case we
139 * wouldn't need to bother with PG_locked and PG_uptodate as nobody will be
140 * accessing anything without owning the mrec_lock mutex. But we do need to
141 * use them because of the read_cache_page() invocation and the code becomes so
142 * much simpler this way that it is well worth it.
143 *
144 * The mft record is now ours and we return a pointer to it. You need to check
145 * the returned pointer with IS_ERR() and if that is true, PTR_ERR() will return
146 * the error code.
147 *
148 * NOTE: Caller is responsible for setting the mft record dirty before calling
149 * unmap_mft_record(). This is obviously only necessary if the caller really
150 * modified the mft record...
151 * Q: Do we want to recycle one of the VFS inode state bits instead?
152 * A: No, the inode ones mean we want to change the mft record, not we want to
153 * write it out.
154 */
155MFT_RECORD *map_mft_record(ntfs_inode *ni)
156{
157    MFT_RECORD *m;
158
159    ntfs_debug("Entering for mft_no 0x%lx.", ni->mft_no);
160
161    /* Make sure the ntfs inode doesn't go away. */
162    atomic_inc(&ni->count);
163
164    /* Serialize access to this mft record. */
165    mutex_lock(&ni->mrec_lock);
166
167    m = map_mft_record_page(ni);
168    if (likely(!IS_ERR(m)))
169        return m;
170
171    mutex_unlock(&ni->mrec_lock);
172    atomic_dec(&ni->count);
173    ntfs_error(ni->vol->sb, "Failed with error code %lu.", -PTR_ERR(m));
174    return m;
175}
176
177/**
178 * unmap_mft_record_page - unmap the page in which a specific mft record resides
179 * @ni: ntfs inode whose mft record page to unmap
180 *
181 * This unmaps the page in which the mft record of the ntfs inode @ni is
182 * situated and returns. This is a NOOP if highmem is not configured.
183 *
184 * The unmap happens via ntfs_unmap_page() which in turn decrements the use
185 * count on the page thus releasing it from the pinned state.
186 *
187 * We do not actually unmap the page from memory of course, as that will be
188 * done by the page cache code itself when memory pressure increases or
189 * whatever.
190 */
191static inline void unmap_mft_record_page(ntfs_inode *ni)
192{
193    BUG_ON(!ni->page);
194
195    // TODO: If dirty, blah...
196    ntfs_unmap_page(ni->page);
197    ni->page = NULL;
198    ni->page_ofs = 0;
199    return;
200}
201
202/**
203 * unmap_mft_record - release a mapped mft record
204 * @ni: ntfs inode whose MFT record to unmap
205 *
206 * We release the page mapping and the mrec_lock mutex which unmaps the mft
207 * record and releases it for others to get hold of. We also release the ntfs
208 * inode by decrementing the ntfs inode reference count.
209 *
210 * NOTE: If caller has modified the mft record, it is imperative to set the mft
211 * record dirty BEFORE calling unmap_mft_record().
212 */
213void unmap_mft_record(ntfs_inode *ni)
214{
215    struct page *page = ni->page;
216
217    BUG_ON(!page);
218
219    ntfs_debug("Entering for mft_no 0x%lx.", ni->mft_no);
220
221    unmap_mft_record_page(ni);
222    mutex_unlock(&ni->mrec_lock);
223    atomic_dec(&ni->count);
224    /*
225     * If pure ntfs_inode, i.e. no vfs inode attached, we leave it to
226     * ntfs_clear_extent_inode() in the extent inode case, and to the
227     * caller in the non-extent, yet pure ntfs inode case, to do the actual
228     * tear down of all structures and freeing of all allocated memory.
229     */
230    return;
231}
232
233/**
234 * map_extent_mft_record - load an extent inode and attach it to its base
235 * @base_ni: base ntfs inode
236 * @mref: mft reference of the extent inode to load
237 * @ntfs_ino: on successful return, pointer to the ntfs_inode structure
238 *
239 * Load the extent mft record @mref and attach it to its base inode @base_ni.
240 * Return the mapped extent mft record if IS_ERR(result) is false. Otherwise
241 * PTR_ERR(result) gives the negative error code.
242 *
243 * On successful return, @ntfs_ino contains a pointer to the ntfs_inode
244 * structure of the mapped extent inode.
245 */
246MFT_RECORD *map_extent_mft_record(ntfs_inode *base_ni, MFT_REF mref,
247        ntfs_inode **ntfs_ino)
248{
249    MFT_RECORD *m;
250    ntfs_inode *ni = NULL;
251    ntfs_inode **extent_nis = NULL;
252    int i;
253    unsigned long mft_no = MREF(mref);
254    u16 seq_no = MSEQNO(mref);
255    bool destroy_ni = false;
256
257    ntfs_debug("Mapping extent mft record 0x%lx (base mft record 0x%lx).",
258            mft_no, base_ni->mft_no);
259    /* Make sure the base ntfs inode doesn't go away. */
260    atomic_inc(&base_ni->count);
261    /*
262     * Check if this extent inode has already been added to the base inode,
263     * in which case just return it. If not found, add it to the base
264     * inode before returning it.
265     */
266    mutex_lock(&base_ni->extent_lock);
267    if (base_ni->nr_extents > 0) {
268        extent_nis = base_ni->ext.extent_ntfs_inos;
269        for (i = 0; i < base_ni->nr_extents; i++) {
270            if (mft_no != extent_nis[i]->mft_no)
271                continue;
272            ni = extent_nis[i];
273            /* Make sure the ntfs inode doesn't go away. */
274            atomic_inc(&ni->count);
275            break;
276        }
277    }
278    if (likely(ni != NULL)) {
279        mutex_unlock(&base_ni->extent_lock);
280        atomic_dec(&base_ni->count);
281        /* We found the record; just have to map and return it. */
282        m = map_mft_record(ni);
283        /* map_mft_record() has incremented this on success. */
284        atomic_dec(&ni->count);
285        if (likely(!IS_ERR(m))) {
286            /* Verify the sequence number. */
287            if (likely(le16_to_cpu(m->sequence_number) == seq_no)) {
288                ntfs_debug("Done 1.");
289                *ntfs_ino = ni;
290                return m;
291            }
292            unmap_mft_record(ni);
293            ntfs_error(base_ni->vol->sb, "Found stale extent mft "
294                    "reference! Corrupt filesystem. "
295                    "Run chkdsk.");
296            return ERR_PTR(-EIO);
297        }
298map_err_out:
299        ntfs_error(base_ni->vol->sb, "Failed to map extent "
300                "mft record, error code %ld.", -PTR_ERR(m));
301        return m;
302    }
303    /* Record wasn't there. Get a new ntfs inode and initialize it. */
304    ni = ntfs_new_extent_inode(base_ni->vol->sb, mft_no);
305    if (unlikely(!ni)) {
306        mutex_unlock(&base_ni->extent_lock);
307        atomic_dec(&base_ni->count);
308        return ERR_PTR(-ENOMEM);
309    }
310    ni->vol = base_ni->vol;
311    ni->seq_no = seq_no;
312    ni->nr_extents = -1;
313    ni->ext.base_ntfs_ino = base_ni;
314    /* Now map the record. */
315    m = map_mft_record(ni);
316    if (IS_ERR(m)) {
317        mutex_unlock(&base_ni->extent_lock);
318        atomic_dec(&base_ni->count);
319        ntfs_clear_extent_inode(ni);
320        goto map_err_out;
321    }
322    /* Verify the sequence number if it is present. */
323    if (seq_no && (le16_to_cpu(m->sequence_number) != seq_no)) {
324        ntfs_error(base_ni->vol->sb, "Found stale extent mft "
325                "reference! Corrupt filesystem. Run chkdsk.");
326        destroy_ni = true;
327        m = ERR_PTR(-EIO);
328        goto unm_err_out;
329    }
330    /* Attach extent inode to base inode, reallocating memory if needed. */
331    if (!(base_ni->nr_extents & 3)) {
332        ntfs_inode **tmp;
333        int new_size = (base_ni->nr_extents + 4) * sizeof(ntfs_inode *);
334
335        tmp = kmalloc(new_size, GFP_NOFS);
336        if (unlikely(!tmp)) {
337            ntfs_error(base_ni->vol->sb, "Failed to allocate "
338                    "internal buffer.");
339            destroy_ni = true;
340            m = ERR_PTR(-ENOMEM);
341            goto unm_err_out;
342        }
343        if (base_ni->nr_extents) {
344            BUG_ON(!base_ni->ext.extent_ntfs_inos);
345            memcpy(tmp, base_ni->ext.extent_ntfs_inos, new_size -
346                    4 * sizeof(ntfs_inode *));
347            kfree(base_ni->ext.extent_ntfs_inos);
348        }
349        base_ni->ext.extent_ntfs_inos = tmp;
350    }
351    base_ni->ext.extent_ntfs_inos[base_ni->nr_extents++] = ni;
352    mutex_unlock(&base_ni->extent_lock);
353    atomic_dec(&base_ni->count);
354    ntfs_debug("Done 2.");
355    *ntfs_ino = ni;
356    return m;
357unm_err_out:
358    unmap_mft_record(ni);
359    mutex_unlock(&base_ni->extent_lock);
360    atomic_dec(&base_ni->count);
361    /*
362     * If the extent inode was not attached to the base inode we need to
363     * release it or we will leak memory.
364     */
365    if (destroy_ni)
366        ntfs_clear_extent_inode(ni);
367    return m;
368}
369
370#ifdef NTFS_RW
371
372/**
373 * __mark_mft_record_dirty - set the mft record and the page containing it dirty
374 * @ni: ntfs inode describing the mapped mft record
375 *
376 * Internal function. Users should call mark_mft_record_dirty() instead.
377 *
378 * Set the mapped (extent) mft record of the (base or extent) ntfs inode @ni,
379 * as well as the page containing the mft record, dirty. Also, mark the base
380 * vfs inode dirty. This ensures that any changes to the mft record are
381 * written out to disk.
382 *
383 * NOTE: We only set I_DIRTY_SYNC and I_DIRTY_DATASYNC (and not I_DIRTY_PAGES)
384 * on the base vfs inode, because even though file data may have been modified,
385 * it is dirty in the inode meta data rather than the data page cache of the
386 * inode, and thus there are no data pages that need writing out. Therefore, a
387 * full mark_inode_dirty() is overkill. A mark_inode_dirty_sync(), on the
388 * other hand, is not sufficient, because ->write_inode needs to be called even
389 * in case of fdatasync. This needs to happen or the file data would not
390 * necessarily hit the device synchronously, even though the vfs inode has the
391 * O_SYNC flag set. Also, I_DIRTY_DATASYNC simply "feels" better than just
392 * I_DIRTY_SYNC, since the file data has not actually hit the block device yet,
393 * which is not what I_DIRTY_SYNC on its own would suggest.
394 */
395void __mark_mft_record_dirty(ntfs_inode *ni)
396{
397    ntfs_inode *base_ni;
398
399    ntfs_debug("Entering for inode 0x%lx.", ni->mft_no);
400    BUG_ON(NInoAttr(ni));
401    mark_ntfs_record_dirty(ni->page, ni->page_ofs);
402    /* Determine the base vfs inode and mark it dirty, too. */
403    mutex_lock(&ni->extent_lock);
404    if (likely(ni->nr_extents >= 0))
405        base_ni = ni;
406    else
407        base_ni = ni->ext.base_ntfs_ino;
408    mutex_unlock(&ni->extent_lock);
409    __mark_inode_dirty(VFS_I(base_ni), I_DIRTY_SYNC | I_DIRTY_DATASYNC);
410}
411
412static const char *ntfs_please_email = "Please email "
413        "linux-ntfs-dev@lists.sourceforge.net and say that you saw "
414        "this message. Thank you.";
415
416/**
417 * ntfs_sync_mft_mirror_umount - synchronise an mft record to the mft mirror
418 * @vol: ntfs volume on which the mft record to synchronize resides
419 * @mft_no: mft record number of mft record to synchronize
420 * @m: mapped, mst protected (extent) mft record to synchronize
421 *
422 * Write the mapped, mst protected (extent) mft record @m with mft record
423 * number @mft_no to the mft mirror ($MFTMirr) of the ntfs volume @vol,
424 * bypassing the page cache and the $MFTMirr inode itself.
425 *
426 * This function is only for use at umount time when the mft mirror inode has
427 * already been disposed off. We BUG() if we are called while the mft mirror
428 * inode is still attached to the volume.
429 *
430 * On success return 0. On error return -errno.
431 *
432 * NOTE: This function is not implemented yet as I am not convinced it can
433 * actually be triggered considering the sequence of commits we do in super.c::
434 * ntfs_put_super(). But just in case we provide this place holder as the
435 * alternative would be either to BUG() or to get a NULL pointer dereference
436 * and Oops.
437 */
438static int ntfs_sync_mft_mirror_umount(ntfs_volume *vol,
439        const unsigned long mft_no, MFT_RECORD *m)
440{
441    BUG_ON(vol->mftmirr_ino);
442    ntfs_error(vol->sb, "Umount time mft mirror syncing is not "
443            "implemented yet. %s", ntfs_please_email);
444    return -EOPNOTSUPP;
445}
446
447/**
448 * ntfs_sync_mft_mirror - synchronize an mft record to the mft mirror
449 * @vol: ntfs volume on which the mft record to synchronize resides
450 * @mft_no: mft record number of mft record to synchronize
451 * @m: mapped, mst protected (extent) mft record to synchronize
452 * @sync: if true, wait for i/o completion
453 *
454 * Write the mapped, mst protected (extent) mft record @m with mft record
455 * number @mft_no to the mft mirror ($MFTMirr) of the ntfs volume @vol.
456 *
457 * On success return 0. On error return -errno and set the volume errors flag
458 * in the ntfs volume @vol.
459 *
460 * NOTE: We always perform synchronous i/o and ignore the @sync parameter.
461 *
462 * TODO: If @sync is false, want to do truly asynchronous i/o, i.e. just
463 * schedule i/o via ->writepage or do it via kntfsd or whatever.
464 */
465int ntfs_sync_mft_mirror(ntfs_volume *vol, const unsigned long mft_no,
466        MFT_RECORD *m, int sync)
467{
468    struct page *page;
469    unsigned int blocksize = vol->sb->s_blocksize;
470    int max_bhs = vol->mft_record_size / blocksize;
471    struct buffer_head *bhs[max_bhs];
472    struct buffer_head *bh, *head;
473    u8 *kmirr;
474    runlist_element *rl;
475    unsigned int block_start, block_end, m_start, m_end, page_ofs;
476    int i_bhs, nr_bhs, err = 0;
477    unsigned char blocksize_bits = vol->sb->s_blocksize_bits;
478
479    ntfs_debug("Entering for inode 0x%lx.", mft_no);
480    BUG_ON(!max_bhs);
481    if (unlikely(!vol->mftmirr_ino)) {
482        /* This could happen during umount... */
483        err = ntfs_sync_mft_mirror_umount(vol, mft_no, m);
484        if (likely(!err))
485            return err;
486        goto err_out;
487    }
488    /* Get the page containing the mirror copy of the mft record @m. */
489    page = ntfs_map_page(vol->mftmirr_ino->i_mapping, mft_no >>
490            (PAGE_CACHE_SHIFT - vol->mft_record_size_bits));
491    if (IS_ERR(page)) {
492        ntfs_error(vol->sb, "Failed to map mft mirror page.");
493        err = PTR_ERR(page);
494        goto err_out;
495    }
496    lock_page(page);
497    BUG_ON(!PageUptodate(page));
498    ClearPageUptodate(page);
499    /* Offset of the mft mirror record inside the page. */
500    page_ofs = (mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
501    /* The address in the page of the mirror copy of the mft record @m. */
502    kmirr = page_address(page) + page_ofs;
503    /* Copy the mst protected mft record to the mirror. */
504    memcpy(kmirr, m, vol->mft_record_size);
505    /* Create uptodate buffers if not present. */
506    if (unlikely(!page_has_buffers(page))) {
507        struct buffer_head *tail;
508
509        bh = head = alloc_page_buffers(page, blocksize, 1);
510        do {
511            set_buffer_uptodate(bh);
512            tail = bh;
513            bh = bh->b_this_page;
514        } while (bh);
515        tail->b_this_page = head;
516        attach_page_buffers(page, head);
517    }
518    bh = head = page_buffers(page);
519    BUG_ON(!bh);
520    rl = NULL;
521    nr_bhs = 0;
522    block_start = 0;
523    m_start = kmirr - (u8*)page_address(page);
524    m_end = m_start + vol->mft_record_size;
525    do {
526        block_end = block_start + blocksize;
527        /* If the buffer is outside the mft record, skip it. */
528        if (block_end <= m_start)
529            continue;
530        if (unlikely(block_start >= m_end))
531            break;
532        /* Need to map the buffer if it is not mapped already. */
533        if (unlikely(!buffer_mapped(bh))) {
534            VCN vcn;
535            LCN lcn;
536            unsigned int vcn_ofs;
537
538            bh->b_bdev = vol->sb->s_bdev;
539            /* Obtain the vcn and offset of the current block. */
540            vcn = ((VCN)mft_no << vol->mft_record_size_bits) +
541                    (block_start - m_start);
542            vcn_ofs = vcn & vol->cluster_size_mask;
543            vcn >>= vol->cluster_size_bits;
544            if (!rl) {
545                down_read(&NTFS_I(vol->mftmirr_ino)->
546                        runlist.lock);
547                rl = NTFS_I(vol->mftmirr_ino)->runlist.rl;
548                /*
549                 * $MFTMirr always has the whole of its runlist
550                 * in memory.
551                 */
552                BUG_ON(!rl);
553            }
554            /* Seek to element containing target vcn. */
555            while (rl->length && rl[1].vcn <= vcn)
556                rl++;
557            lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
558            /* For $MFTMirr, only lcn >= 0 is a successful remap. */
559            if (likely(lcn >= 0)) {
560                /* Setup buffer head to correct block. */
561                bh->b_blocknr = ((lcn <<
562                        vol->cluster_size_bits) +
563                        vcn_ofs) >> blocksize_bits;
564                set_buffer_mapped(bh);
565            } else {
566                bh->b_blocknr = -1;
567                ntfs_error(vol->sb, "Cannot write mft mirror "
568                        "record 0x%lx because its "
569                        "location on disk could not "
570                        "be determined (error code "
571                        "%lli).", mft_no,
572                        (long long)lcn);
573                err = -EIO;
574            }
575        }
576        BUG_ON(!buffer_uptodate(bh));
577        BUG_ON(!nr_bhs && (m_start != block_start));
578        BUG_ON(nr_bhs >= max_bhs);
579        bhs[nr_bhs++] = bh;
580        BUG_ON((nr_bhs >= max_bhs) && (m_end != block_end));
581    } while (block_start = block_end, (bh = bh->b_this_page) != head);
582    if (unlikely(rl))
583        up_read(&NTFS_I(vol->mftmirr_ino)->runlist.lock);
584    if (likely(!err)) {
585        /* Lock buffers and start synchronous write i/o on them. */
586        for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
587            struct buffer_head *tbh = bhs[i_bhs];
588
589            if (!trylock_buffer(tbh))
590                BUG();
591            BUG_ON(!buffer_uptodate(tbh));
592            clear_buffer_dirty(tbh);
593            get_bh(tbh);
594            tbh->b_end_io = end_buffer_write_sync;
595            submit_bh(WRITE, tbh);
596        }
597        /* Wait on i/o completion of buffers. */
598        for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
599            struct buffer_head *tbh = bhs[i_bhs];
600
601            wait_on_buffer(tbh);
602            if (unlikely(!buffer_uptodate(tbh))) {
603                err = -EIO;
604                /*
605                 * Set the buffer uptodate so the page and
606                 * buffer states do not become out of sync.
607                 */
608                set_buffer_uptodate(tbh);
609            }
610        }
611    } else /* if (unlikely(err)) */ {
612        /* Clean the buffers. */
613        for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++)
614            clear_buffer_dirty(bhs[i_bhs]);
615    }
616    /* Current state: all buffers are clean, unlocked, and uptodate. */
617    /* Remove the mst protection fixups again. */
618    post_write_mst_fixup((NTFS_RECORD*)kmirr);
619    flush_dcache_page(page);
620    SetPageUptodate(page);
621    unlock_page(page);
622    ntfs_unmap_page(page);
623    if (likely(!err)) {
624        ntfs_debug("Done.");
625    } else {
626        ntfs_error(vol->sb, "I/O error while writing mft mirror "
627                "record 0x%lx!", mft_no);
628err_out:
629        ntfs_error(vol->sb, "Failed to synchronize $MFTMirr (error "
630                "code %i). Volume will be left marked dirty "
631                "on umount. Run ntfsfix on the partition "
632                "after umounting to correct this.", -err);
633        NVolSetErrors(vol);
634    }
635    return err;
636}
637
638/**
639 * write_mft_record_nolock - write out a mapped (extent) mft record
640 * @ni: ntfs inode describing the mapped (extent) mft record
641 * @m: mapped (extent) mft record to write
642 * @sync: if true, wait for i/o completion
643 *
644 * Write the mapped (extent) mft record @m described by the (regular or extent)
645 * ntfs inode @ni to backing store. If the mft record @m has a counterpart in
646 * the mft mirror, that is also updated.
647 *
648 * We only write the mft record if the ntfs inode @ni is dirty and the first
649 * buffer belonging to its mft record is dirty, too. We ignore the dirty state
650 * of subsequent buffers because we could have raced with
651 * fs/ntfs/aops.c::mark_ntfs_record_dirty().
652 *
653 * On success, clean the mft record and return 0. On error, leave the mft
654 * record dirty and return -errno.
655 *
656 * NOTE: We always perform synchronous i/o and ignore the @sync parameter.
657 * However, if the mft record has a counterpart in the mft mirror and @sync is
658 * true, we write the mft record, wait for i/o completion, and only then write
659 * the mft mirror copy. This ensures that if the system crashes either the mft
660 * or the mft mirror will contain a self-consistent mft record @m. If @sync is
661 * false on the other hand, we start i/o on both and then wait for completion
662 * on them. This provides a speedup but no longer guarantees that you will end
663 * up with a self-consistent mft record in the case of a crash but if you asked
664 * for asynchronous writing you probably do not care about that anyway.
665 *
666 * TODO: If @sync is false, want to do truly asynchronous i/o, i.e. just
667 * schedule i/o via ->writepage or do it via kntfsd or whatever.
668 */
669int write_mft_record_nolock(ntfs_inode *ni, MFT_RECORD *m, int sync)
670{
671    ntfs_volume *vol = ni->vol;
672    struct page *page = ni->page;
673    unsigned int blocksize = vol->sb->s_blocksize;
674    unsigned char blocksize_bits = vol->sb->s_blocksize_bits;
675    int max_bhs = vol->mft_record_size / blocksize;
676    struct buffer_head *bhs[max_bhs];
677    struct buffer_head *bh, *head;
678    runlist_element *rl;
679    unsigned int block_start, block_end, m_start, m_end;
680    int i_bhs, nr_bhs, err = 0;
681
682    ntfs_debug("Entering for inode 0x%lx.", ni->mft_no);
683    BUG_ON(NInoAttr(ni));
684    BUG_ON(!max_bhs);
685    BUG_ON(!PageLocked(page));
686    /*
687     * If the ntfs_inode is clean no need to do anything. If it is dirty,
688     * mark it as clean now so that it can be redirtied later on if needed.
689     * There is no danger of races since the caller is holding the locks
690     * for the mft record @m and the page it is in.
691     */
692    if (!NInoTestClearDirty(ni))
693        goto done;
694    bh = head = page_buffers(page);
695    BUG_ON(!bh);
696    rl = NULL;
697    nr_bhs = 0;
698    block_start = 0;
699    m_start = ni->page_ofs;
700    m_end = m_start + vol->mft_record_size;
701    do {
702        block_end = block_start + blocksize;
703        /* If the buffer is outside the mft record, skip it. */
704        if (block_end <= m_start)
705            continue;
706        if (unlikely(block_start >= m_end))
707            break;
708        /*
709         * If this block is not the first one in the record, we ignore
710         * the buffer's dirty state because we could have raced with a
711         * parallel mark_ntfs_record_dirty().
712         */
713        if (block_start == m_start) {
714            /* This block is the first one in the record. */
715            if (!buffer_dirty(bh)) {
716                BUG_ON(nr_bhs);
717                /* Clean records are not written out. */
718                break;
719            }
720        }
721        /* Need to map the buffer if it is not mapped already. */
722        if (unlikely(!buffer_mapped(bh))) {
723            VCN vcn;
724            LCN lcn;
725            unsigned int vcn_ofs;
726
727            bh->b_bdev = vol->sb->s_bdev;
728            /* Obtain the vcn and offset of the current block. */
729            vcn = ((VCN)ni->mft_no << vol->mft_record_size_bits) +
730                    (block_start - m_start);
731            vcn_ofs = vcn & vol->cluster_size_mask;
732            vcn >>= vol->cluster_size_bits;
733            if (!rl) {
734                down_read(&NTFS_I(vol->mft_ino)->runlist.lock);
735                rl = NTFS_I(vol->mft_ino)->runlist.rl;
736                BUG_ON(!rl);
737            }
738            /* Seek to element containing target vcn. */
739            while (rl->length && rl[1].vcn <= vcn)
740                rl++;
741            lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
742            /* For $MFT, only lcn >= 0 is a successful remap. */
743            if (likely(lcn >= 0)) {
744                /* Setup buffer head to correct block. */
745                bh->b_blocknr = ((lcn <<
746                        vol->cluster_size_bits) +
747                        vcn_ofs) >> blocksize_bits;
748                set_buffer_mapped(bh);
749            } else {
750                bh->b_blocknr = -1;
751                ntfs_error(vol->sb, "Cannot write mft record "
752                        "0x%lx because its location "
753                        "on disk could not be "
754                        "determined (error code %lli).",
755                        ni->mft_no, (long long)lcn);
756                err = -EIO;
757            }
758        }
759        BUG_ON(!buffer_uptodate(bh));
760        BUG_ON(!nr_bhs && (m_start != block_start));
761        BUG_ON(nr_bhs >= max_bhs);
762        bhs[nr_bhs++] = bh;
763        BUG_ON((nr_bhs >= max_bhs) && (m_end != block_end));
764    } while (block_start = block_end, (bh = bh->b_this_page) != head);
765    if (unlikely(rl))
766        up_read(&NTFS_I(vol->mft_ino)->runlist.lock);
767    if (!nr_bhs)
768        goto done;
769    if (unlikely(err))
770        goto cleanup_out;
771    /* Apply the mst protection fixups. */
772    err = pre_write_mst_fixup((NTFS_RECORD*)m, vol->mft_record_size);
773    if (err) {
774        ntfs_error(vol->sb, "Failed to apply mst fixups!");
775        goto cleanup_out;
776    }
777    flush_dcache_mft_record_page(ni);
778    /* Lock buffers and start synchronous write i/o on them. */
779    for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
780        struct buffer_head *tbh = bhs[i_bhs];
781
782        if (!trylock_buffer(tbh))
783            BUG();
784        BUG_ON(!buffer_uptodate(tbh));
785        clear_buffer_dirty(tbh);
786        get_bh(tbh);
787        tbh->b_end_io = end_buffer_write_sync;
788        submit_bh(WRITE, tbh);
789    }
790    /* Synchronize the mft mirror now if not @sync. */
791    if (!sync && ni->mft_no < vol->mftmirr_size)
792        ntfs_sync_mft_mirror(vol, ni->mft_no, m, sync);
793    /* Wait on i/o completion of buffers. */
794    for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
795        struct buffer_head *tbh = bhs[i_bhs];
796
797        wait_on_buffer(tbh);
798        if (unlikely(!buffer_uptodate(tbh))) {
799            err = -EIO;
800            /*
801             * Set the buffer uptodate so the page and buffer
802             * states do not become out of sync.
803             */
804            if (PageUptodate(page))
805                set_buffer_uptodate(tbh);
806        }
807    }
808    /* If @sync, now synchronize the mft mirror. */
809    if (sync && ni->mft_no < vol->mftmirr_size)
810        ntfs_sync_mft_mirror(vol, ni->mft_no, m, sync);
811    /* Remove the mst protection fixups again. */
812    post_write_mst_fixup((NTFS_RECORD*)m);
813    flush_dcache_mft_record_page(ni);
814    if (unlikely(err)) {
815        /* I/O error during writing. This is really bad! */
816        ntfs_error(vol->sb, "I/O error while writing mft record "
817                "0x%lx! Marking base inode as bad. You "
818                "should unmount the volume and run chkdsk.",
819                ni->mft_no);
820        goto err_out;
821    }
822done:
823    ntfs_debug("Done.");
824    return 0;
825cleanup_out:
826    /* Clean the buffers. */
827    for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++)
828        clear_buffer_dirty(bhs[i_bhs]);
829err_out:
830    /*
831     * Current state: all buffers are clean, unlocked, and uptodate.
832     * The caller should mark the base inode as bad so that no more i/o
833     * happens. ->clear_inode() will still be invoked so all extent inodes
834     * and other allocated memory will be freed.
835     */
836    if (err == -ENOMEM) {
837        ntfs_error(vol->sb, "Not enough memory to write mft record. "
838                "Redirtying so the write is retried later.");
839        mark_mft_record_dirty(ni);
840        err = 0;
841    } else
842        NVolSetErrors(vol);
843    return err;
844}
845
846/**
847 * ntfs_may_write_mft_record - check if an mft record may be written out
848 * @vol: [IN] ntfs volume on which the mft record to check resides
849 * @mft_no: [IN] mft record number of the mft record to check
850 * @m: [IN] mapped mft record to check
851 * @locked_ni: [OUT] caller has to unlock this ntfs inode if one is returned
852 *
853 * Check if the mapped (base or extent) mft record @m with mft record number
854 * @mft_no belonging to the ntfs volume @vol may be written out. If necessary
855 * and possible the ntfs inode of the mft record is locked and the base vfs
856 * inode is pinned. The locked ntfs inode is then returned in @locked_ni. The
857 * caller is responsible for unlocking the ntfs inode and unpinning the base
858 * vfs inode.
859 *
860 * Return 'true' if the mft record may be written out and 'false' if not.
861 *
862 * The caller has locked the page and cleared the uptodate flag on it which
863 * means that we can safely write out any dirty mft records that do not have
864 * their inodes in icache as determined by ilookup5() as anyone
865 * opening/creating such an inode would block when attempting to map the mft
866 * record in read_cache_page() until we are finished with the write out.
867 *
868 * Here is a description of the tests we perform:
869 *
870 * If the inode is found in icache we know the mft record must be a base mft
871 * record. If it is dirty, we do not write it and return 'false' as the vfs
872 * inode write paths will result in the access times being updated which would
873 * cause the base mft record to be redirtied and written out again. (We know
874 * the access time update will modify the base mft record because Windows
875 * chkdsk complains if the standard information attribute is not in the base
876 * mft record.)
877 *
878 * If the inode is in icache and not dirty, we attempt to lock the mft record
879 * and if we find the lock was already taken, it is not safe to write the mft
880 * record and we return 'false'.
881 *
882 * If we manage to obtain the lock we have exclusive access to the mft record,
883 * which also allows us safe writeout of the mft record. We then set
884 * @locked_ni to the locked ntfs inode and return 'true'.
885 *
886 * Note we cannot just lock the mft record and sleep while waiting for the lock
887 * because this would deadlock due to lock reversal (normally the mft record is
888 * locked before the page is locked but we already have the page locked here
889 * when we try to lock the mft record).
890 *
891 * If the inode is not in icache we need to perform further checks.
892 *
893 * If the mft record is not a FILE record or it is a base mft record, we can
894 * safely write it and return 'true'.
895 *
896 * We now know the mft record is an extent mft record. We check if the inode
897 * corresponding to its base mft record is in icache and obtain a reference to
898 * it if it is. If it is not, we can safely write it and return 'true'.
899 *
900 * We now have the base inode for the extent mft record. We check if it has an
901 * ntfs inode for the extent mft record attached and if not it is safe to write
902 * the extent mft record and we return 'true'.
903 *
904 * The ntfs inode for the extent mft record is attached to the base inode so we
905 * attempt to lock the extent mft record and if we find the lock was already
906 * taken, it is not safe to write the extent mft record and we return 'false'.
907 *
908 * If we manage to obtain the lock we have exclusive access to the extent mft
909 * record, which also allows us safe writeout of the extent mft record. We
910 * set the ntfs inode of the extent mft record clean and then set @locked_ni to
911 * the now locked ntfs inode and return 'true'.
912 *
913 * Note, the reason for actually writing dirty mft records here and not just
914 * relying on the vfs inode dirty code paths is that we can have mft records
915 * modified without them ever having actual inodes in memory. Also we can have
916 * dirty mft records with clean ntfs inodes in memory. None of the described
917 * cases would result in the dirty mft records being written out if we only
918 * relied on the vfs inode dirty code paths. And these cases can really occur
919 * during allocation of new mft records and in particular when the
920 * initialized_size of the $MFT/$DATA attribute is extended and the new space
921 * is initialized using ntfs_mft_record_format(). The clean inode can then
922 * appear if the mft record is reused for a new inode before it got written
923 * out.
924 */
925bool ntfs_may_write_mft_record(ntfs_volume *vol, const unsigned long mft_no,
926        const MFT_RECORD *m, ntfs_inode **locked_ni)
927{
928    struct super_block *sb = vol->sb;
929    struct inode *mft_vi = vol->mft_ino;
930    struct inode *vi;
931    ntfs_inode *ni, *eni, **extent_nis;
932    int i;
933    ntfs_attr na;
934
935    ntfs_debug("Entering for inode 0x%lx.", mft_no);
936    /*
937     * Normally we do not return a locked inode so set @locked_ni to NULL.
938     */
939    BUG_ON(!locked_ni);
940    *locked_ni = NULL;
941    /*
942     * Check if the inode corresponding to this mft record is in the VFS
943     * inode cache and obtain a reference to it if it is.
944     */
945    ntfs_debug("Looking for inode 0x%lx in icache.", mft_no);
946    na.mft_no = mft_no;
947    na.name = NULL;
948    na.name_len = 0;
949    na.type = AT_UNUSED;
950    /*
951     * Optimize inode 0, i.e. $MFT itself, since we have it in memory and
952     * we get here for it rather often.
953     */
954    if (!mft_no) {
955        /* Balance the below iput(). */
956        vi = igrab(mft_vi);
957        BUG_ON(vi != mft_vi);
958    } else {
959        /*
960         * Have to use ilookup5_nowait() since ilookup5() waits for the
961         * inode lock which causes ntfs to deadlock when a concurrent
962         * inode write via the inode dirty code paths and the page
963         * dirty code path of the inode dirty code path when writing
964         * $MFT occurs.
965         */
966        vi = ilookup5_nowait(sb, mft_no, (test_t)ntfs_test_inode, &na);
967    }
968    if (vi) {
969        ntfs_debug("Base inode 0x%lx is in icache.", mft_no);
970        /* The inode is in icache. */
971        ni = NTFS_I(vi);
972        /* Take a reference to the ntfs inode. */
973        atomic_inc(&ni->count);
974        /* If the inode is dirty, do not write this record. */
975        if (NInoDirty(ni)) {
976            ntfs_debug("Inode 0x%lx is dirty, do not write it.",
977                    mft_no);
978            atomic_dec(&ni->count);
979            iput(vi);
980            return false;
981        }
982        ntfs_debug("Inode 0x%lx is not dirty.", mft_no);
983        /* The inode is not dirty, try to take the mft record lock. */
984        if (unlikely(!mutex_trylock(&ni->mrec_lock))) {
985            ntfs_debug("Mft record 0x%lx is already locked, do "
986                    "not write it.", mft_no);
987            atomic_dec(&ni->count);
988            iput(vi);
989            return false;
990        }
991        ntfs_debug("Managed to lock mft record 0x%lx, write it.",
992                mft_no);
993        /*
994         * The write has to occur while we hold the mft record lock so
995         * return the locked ntfs inode.
996         */
997        *locked_ni = ni;
998        return true;
999    }
1000    ntfs_debug("Inode 0x%lx is not in icache.", mft_no);
1001    /* The inode is not in icache. */
1002    /* Write the record if it is not a mft record (type "FILE"). */
1003    if (!ntfs_is_mft_record(m->magic)) {
1004        ntfs_debug("Mft record 0x%lx is not a FILE record, write it.",
1005                mft_no);
1006        return true;
1007    }
1008    /* Write the mft record if it is a base inode. */
1009    if (!m->base_mft_record) {
1010        ntfs_debug("Mft record 0x%lx is a base record, write it.",
1011                mft_no);
1012        return true;
1013    }
1014    /*
1015     * This is an extent mft record. Check if the inode corresponding to
1016     * its base mft record is in icache and obtain a reference to it if it
1017     * is.
1018     */
1019    na.mft_no = MREF_LE(m->base_mft_record);
1020    ntfs_debug("Mft record 0x%lx is an extent record. Looking for base "
1021            "inode 0x%lx in icache.", mft_no, na.mft_no);
1022    if (!na.mft_no) {
1023        /* Balance the below iput(). */
1024        vi = igrab(mft_vi);
1025        BUG_ON(vi != mft_vi);
1026    } else
1027        vi = ilookup5_nowait(sb, na.mft_no, (test_t)ntfs_test_inode,
1028                &na);
1029    if (!vi) {
1030        /*
1031         * The base inode is not in icache, write this extent mft
1032         * record.
1033         */
1034        ntfs_debug("Base inode 0x%lx is not in icache, write the "
1035                "extent record.", na.mft_no);
1036        return true;
1037    }
1038    ntfs_debug("Base inode 0x%lx is in icache.", na.mft_no);
1039    /*
1040     * The base inode is in icache. Check if it has the extent inode
1041     * corresponding to this extent mft record attached.
1042     */
1043    ni = NTFS_I(vi);
1044    mutex_lock(&ni->extent_lock);
1045    if (ni->nr_extents <= 0) {
1046        /*
1047         * The base inode has no attached extent inodes, write this
1048         * extent mft record.
1049         */
1050        mutex_unlock(&ni->extent_lock);
1051        iput(vi);
1052        ntfs_debug("Base inode 0x%lx has no attached extent inodes, "
1053                "write the extent record.", na.mft_no);
1054        return true;
1055    }
1056    /* Iterate over the attached extent inodes. */
1057    extent_nis = ni->ext.extent_ntfs_inos;
1058    for (eni = NULL, i = 0; i < ni->nr_extents; ++i) {
1059        if (mft_no == extent_nis[i]->mft_no) {
1060            /*
1061             * Found the extent inode corresponding to this extent
1062             * mft record.
1063             */
1064            eni = extent_nis[i];
1065            break;
1066        }
1067    }
1068    /*
1069     * If the extent inode was not attached to the base inode, write this
1070     * extent mft record.
1071     */
1072    if (!eni) {
1073        mutex_unlock(&ni->extent_lock);
1074        iput(vi);
1075        ntfs_debug("Extent inode 0x%lx is not attached to its base "
1076                "inode 0x%lx, write the extent record.",
1077                mft_no, na.mft_no);
1078        return true;
1079    }
1080    ntfs_debug("Extent inode 0x%lx is attached to its base inode 0x%lx.",
1081            mft_no, na.mft_no);
1082    /* Take a reference to the extent ntfs inode. */
1083    atomic_inc(&eni->count);
1084    mutex_unlock(&ni->extent_lock);
1085    /*
1086     * Found the extent inode coresponding to this extent mft record.
1087     * Try to take the mft record lock.
1088     */
1089    if (unlikely(!mutex_trylock(&eni->mrec_lock))) {
1090        atomic_dec(&eni->count);
1091        iput(vi);
1092        ntfs_debug("Extent mft record 0x%lx is already locked, do "
1093                "not write it.", mft_no);
1094        return false;
1095    }
1096    ntfs_debug("Managed to lock extent mft record 0x%lx, write it.",
1097            mft_no);
1098    if (NInoTestClearDirty(eni))
1099        ntfs_debug("Extent inode 0x%lx is dirty, marking it clean.",
1100                mft_no);
1101    /*
1102     * The write has to occur while we hold the mft record lock so return
1103     * the locked extent ntfs inode.
1104     */
1105    *locked_ni = eni;
1106    return true;
1107}
1108
1109static const char *es = " Leaving inconsistent metadata. Unmount and run "
1110        "chkdsk.";
1111
1112/**
1113 * ntfs_mft_bitmap_find_and_alloc_free_rec_nolock - see name
1114 * @vol: volume on which to search for a free mft record
1115 * @base_ni: open base inode if allocating an extent mft record or NULL
1116 *
1117 * Search for a free mft record in the mft bitmap attribute on the ntfs volume
1118 * @vol.
1119 *
1120 * If @base_ni is NULL start the search at the default allocator position.
1121 *
1122 * If @base_ni is not NULL start the search at the mft record after the base
1123 * mft record @base_ni.
1124 *
1125 * Return the free mft record on success and -errno on error. An error code of
1126 * -ENOSPC means that there are no free mft records in the currently
1127 * initialized mft bitmap.
1128 *
1129 * Locking: Caller must hold vol->mftbmp_lock for writing.
1130 */
1131static int ntfs_mft_bitmap_find_and_alloc_free_rec_nolock(ntfs_volume *vol,
1132        ntfs_inode *base_ni)
1133{
1134    s64 pass_end, ll, data_pos, pass_start, ofs, bit;
1135    unsigned long flags;
1136    struct address_space *mftbmp_mapping;
1137    u8 *buf, *byte;
1138    struct page *page;
1139    unsigned int page_ofs, size;
1140    u8 pass, b;
1141
1142    ntfs_debug("Searching for free mft record in the currently "
1143            "initialized mft bitmap.");
1144    mftbmp_mapping = vol->mftbmp_ino->i_mapping;
1145    /*
1146     * Set the end of the pass making sure we do not overflow the mft
1147     * bitmap.
1148     */
1149    read_lock_irqsave(&NTFS_I(vol->mft_ino)->size_lock, flags);
1150    pass_end = NTFS_I(vol->mft_ino)->allocated_size >>
1151            vol->mft_record_size_bits;
1152    read_unlock_irqrestore(&NTFS_I(vol->mft_ino)->size_lock, flags);
1153    read_lock_irqsave(&NTFS_I(vol->mftbmp_ino)->size_lock, flags);
1154    ll = NTFS_I(vol->mftbmp_ino)->initialized_size << 3;
1155    read_unlock_irqrestore(&NTFS_I(vol->mftbmp_ino)->size_lock, flags);
1156    if (pass_end > ll)
1157        pass_end = ll;
1158    pass = 1;
1159    if (!base_ni)
1160        data_pos = vol->mft_data_pos;
1161    else
1162        data_pos = base_ni->mft_no + 1;
1163    if (data_pos < 24)
1164        data_pos = 24;
1165    if (data_pos >= pass_end) {
1166        data_pos = 24;
1167        pass = 2;
1168        /* This happens on a freshly formatted volume. */
1169        if (data_pos >= pass_end)
1170            return -ENOSPC;
1171    }
1172    pass_start = data_pos;
1173    ntfs_debug("Starting bitmap search: pass %u, pass_start 0x%llx, "
1174            "pass_end 0x%llx, data_pos 0x%llx.", pass,
1175            (long long)pass_start, (long long)pass_end,
1176            (long long)data_pos);
1177    /* Loop until a free mft record is found. */
1178    for (; pass <= 2;) {
1179        /* Cap size to pass_end. */
1180        ofs = data_pos >> 3;
1181        page_ofs = ofs & ~PAGE_CACHE_MASK;
1182        size = PAGE_CACHE_SIZE - page_ofs;
1183        ll = ((pass_end + 7) >> 3) - ofs;
1184        if (size > ll)
1185            size = ll;
1186        size <<= 3;
1187        /*
1188         * If we are still within the active pass, search the next page
1189         * for a zero bit.
1190         */
1191        if (size) {
1192            page = ntfs_map_page(mftbmp_mapping,
1193                    ofs >> PAGE_CACHE_SHIFT);
1194            if (IS_ERR(page)) {
1195                ntfs_error(vol->sb, "Failed to read mft "
1196                        "bitmap, aborting.");
1197                return PTR_ERR(page);
1198            }
1199            buf = (u8*)page_address(page) + page_ofs;
1200            bit = data_pos & 7;
1201            data_pos &= ~7ull;
1202            ntfs_debug("Before inner for loop: size 0x%x, "
1203                    "data_pos 0x%llx, bit 0x%llx", size,
1204                    (long long)data_pos, (long long)bit);
1205            for (; bit < size && data_pos + bit < pass_end;
1206                    bit &= ~7ull, bit += 8) {
1207                byte = buf + (bit >> 3);
1208                if (*byte == 0xff)
1209                    continue;
1210                b = ffz((unsigned long)*byte);
1211                if (b < 8 && b >= (bit & 7)) {
1212                    ll = data_pos + (bit & ~7ull) + b;
1213                    if (unlikely(ll > (1ll << 32))) {
1214                        ntfs_unmap_page(page);
1215                        return -ENOSPC;
1216                    }
1217                    *byte |= 1 << b;
1218                    flush_dcache_page(page);
1219                    set_page_dirty(page);
1220                    ntfs_unmap_page(page);
1221                    ntfs_debug("Done. (Found and "
1222                            "allocated mft record "
1223                            "0x%llx.)",
1224                            (long long)ll);
1225                    return ll;
1226                }
1227            }
1228            ntfs_debug("After inner for loop: size 0x%x, "
1229                    "data_pos 0x%llx, bit 0x%llx", size,
1230                    (long long)data_pos, (long long)bit);
1231            data_pos += size;
1232            ntfs_unmap_page(page);
1233            /*
1234             * If the end of the pass has not been reached yet,
1235             * continue searching the mft bitmap for a zero bit.
1236             */
1237            if (data_pos < pass_end)
1238                continue;
1239        }
1240        /* Do the next pass. */
1241        if (++pass == 2) {
1242            /*
1243             * Starting the second pass, in which we scan the first
1244             * part of the zone which we omitted earlier.
1245             */
1246            pass_end = pass_start;
1247            data_pos = pass_start = 24;
1248            ntfs_debug("pass %i, pass_start 0x%llx, pass_end "
1249                    "0x%llx.", pass, (long long)pass_start,
1250                    (long long)pass_end);
1251            if (data_pos >= pass_end)
1252                break;
1253        }
1254    }
1255    /* No free mft records in currently initialized mft bitmap. */
1256    ntfs_debug("Done. (No free mft records left in currently initialized "
1257            "mft bitmap.)");
1258    return -ENOSPC;
1259}
1260
1261/**
1262 * ntfs_mft_bitmap_extend_allocation_nolock - extend mft bitmap by a cluster
1263 * @vol: volume on which to extend the mft bitmap attribute
1264 *
1265 * Extend the mft bitmap attribute on the ntfs volume @vol by one cluster.
1266 *
1267 * Note: Only changes allocated_size, i.e. does not touch initialized_size or
1268 * data_size.
1269 *
1270 * Return 0 on success and -errno on error.
1271 *
1272 * Locking: - Caller must hold vol->mftbmp_lock for writing.
1273 * - This function takes NTFS_I(vol->mftbmp_ino)->runlist.lock for
1274 * writing and releases it before returning.
1275 * - This function takes vol->lcnbmp_lock for writing and releases it
1276 * before returning.
1277 */
1278static int ntfs_mft_bitmap_extend_allocation_nolock(ntfs_volume *vol)
1279{
1280    LCN lcn;
1281    s64 ll;
1282    unsigned long flags;
1283    struct page *page;
1284    ntfs_inode *mft_ni, *mftbmp_ni;
1285    runlist_element *rl, *rl2 = NULL;
1286    ntfs_attr_search_ctx *ctx = NULL;
1287    MFT_RECORD *mrec;
1288    ATTR_RECORD *a = NULL;
1289    int ret, mp_size;
1290    u32 old_alen = 0;
1291    u8 *b, tb;
1292    struct {
1293        u8 added_cluster:1;
1294        u8 added_run:1;
1295        u8 mp_rebuilt:1;
1296    } status = { 0, 0, 0 };
1297
1298    ntfs_debug("Extending mft bitmap allocation.");
1299    mft_ni = NTFS_I(vol->mft_ino);
1300    mftbmp_ni = NTFS_I(vol->mftbmp_ino);
1301    /*
1302     * Determine the last lcn of the mft bitmap. The allocated size of the
1303     * mft bitmap cannot be zero so we are ok to do this.
1304     */
1305    down_write(&mftbmp_ni->runlist.lock);
1306    read_lock_irqsave(&mftbmp_ni->size_lock, flags);
1307    ll = mftbmp_ni->allocated_size;
1308    read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
1309    rl = ntfs_attr_find_vcn_nolock(mftbmp_ni,
1310            (ll - 1) >> vol->cluster_size_bits, NULL);
1311    if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
1312        up_write(&mftbmp_ni->runlist.lock);
1313        ntfs_error(vol->sb, "Failed to determine last allocated "
1314                "cluster of mft bitmap attribute.");
1315        if (!IS_ERR(rl))
1316            ret = -EIO;
1317        else
1318            ret = PTR_ERR(rl);
1319        return ret;
1320    }
1321    lcn = rl->lcn + rl->length;
1322    ntfs_debug("Last lcn of mft bitmap attribute is 0x%llx.",
1323            (long long)lcn);
1324    /*
1325     * Attempt to get the cluster following the last allocated cluster by
1326     * hand as it may be in the MFT zone so the allocator would not give it
1327     * to us.
1328     */
1329    ll = lcn >> 3;
1330    page = ntfs_map_page(vol->lcnbmp_ino->i_mapping,
1331            ll >> PAGE_CACHE_SHIFT);
1332    if (IS_ERR(page)) {
1333        up_write(&mftbmp_ni->runlist.lock);
1334        ntfs_error(vol->sb, "Failed to read from lcn bitmap.");
1335        return PTR_ERR(page);
1336    }
1337    b = (u8*)page_address(page) + (ll & ~PAGE_CACHE_MASK);
1338    tb = 1 << (lcn & 7ull);
1339    down_write(&vol->lcnbmp_lock);
1340    if (*b != 0xff && !(*b & tb)) {
1341        /* Next cluster is free, allocate it. */
1342        *b |= tb;
1343        flush_dcache_page(page);
1344        set_page_dirty(page);
1345        up_write(&vol->lcnbmp_lock);
1346        ntfs_unmap_page(page);
1347        /* Update the mft bitmap runlist. */
1348        rl->length++;
1349        rl[1].vcn++;
1350        status.added_cluster = 1;
1351        ntfs_debug("Appending one cluster to mft bitmap.");
1352    } else {
1353        up_write(&vol->lcnbmp_lock);
1354        ntfs_unmap_page(page);
1355        /* Allocate a cluster from the DATA_ZONE. */
1356        rl2 = ntfs_cluster_alloc(vol, rl[1].vcn, 1, lcn, DATA_ZONE,
1357                true);
1358        if (IS_ERR(rl2)) {
1359            up_write(&mftbmp_ni->runlist.lock);
1360            ntfs_error(vol->sb, "Failed to allocate a cluster for "
1361                    "the mft bitmap.");
1362            return PTR_ERR(rl2);
1363        }
1364        rl = ntfs_runlists_merge(mftbmp_ni->runlist.rl, rl2);
1365        if (IS_ERR(rl)) {
1366            up_write(&mftbmp_ni->runlist.lock);
1367            ntfs_error(vol->sb, "Failed to merge runlists for mft "
1368                    "bitmap.");
1369            if (ntfs_cluster_free_from_rl(vol, rl2)) {
1370                ntfs_error(vol->sb, "Failed to dealocate "
1371                        "allocated cluster.%s", es);
1372                NVolSetErrors(vol);
1373            }
1374            ntfs_free(rl2);
1375            return PTR_ERR(rl);
1376        }
1377        mftbmp_ni->runlist.rl = rl;
1378        status.added_run = 1;
1379        ntfs_debug("Adding one run to mft bitmap.");
1380        /* Find the last run in the new runlist. */
1381        for (; rl[1].length; rl++)
1382            ;
1383    }
1384    /*
1385     * Update the attribute record as well. Note: @rl is the last
1386     * (non-terminator) runlist element of mft bitmap.
1387     */
1388    mrec = map_mft_record(mft_ni);
1389    if (IS_ERR(mrec)) {
1390        ntfs_error(vol->sb, "Failed to map mft record.");
1391        ret = PTR_ERR(mrec);
1392        goto undo_alloc;
1393    }
1394    ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
1395    if (unlikely(!ctx)) {
1396        ntfs_error(vol->sb, "Failed to get search context.");
1397        ret = -ENOMEM;
1398        goto undo_alloc;
1399    }
1400    ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
1401            mftbmp_ni->name_len, CASE_SENSITIVE, rl[1].vcn, NULL,
1402            0, ctx);
1403    if (unlikely(ret)) {
1404        ntfs_error(vol->sb, "Failed to find last attribute extent of "
1405                "mft bitmap attribute.");
1406        if (ret == -ENOENT)
1407            ret = -EIO;
1408        goto undo_alloc;
1409    }
1410    a = ctx->attr;
1411    ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
1412    /* Search back for the previous last allocated cluster of mft bitmap. */
1413    for (rl2 = rl; rl2 > mftbmp_ni->runlist.rl; rl2--) {
1414        if (ll >= rl2->vcn)
1415            break;
1416    }
1417    BUG_ON(ll < rl2->vcn);
1418    BUG_ON(ll >= rl2->vcn + rl2->length);
1419    /* Get the size for the new mapping pairs array for this extent. */
1420    mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll, -1);
1421    if (unlikely(mp_size <= 0)) {
1422        ntfs_error(vol->sb, "Get size for mapping pairs failed for "
1423                "mft bitmap attribute extent.");
1424        ret = mp_size;
1425        if (!ret)
1426            ret = -EIO;
1427        goto undo_alloc;
1428    }
1429    /* Expand the attribute record if necessary. */
1430    old_alen = le32_to_cpu(a->length);
1431    ret = ntfs_attr_record_resize(ctx->mrec, a, mp_size +
1432            le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
1433    if (unlikely(ret)) {
1434        if (ret != -ENOSPC) {
1435            ntfs_error(vol->sb, "Failed to resize attribute "
1436                    "record for mft bitmap attribute.");
1437            goto undo_alloc;
1438        }
1439        // TODO: Deal with this by moving this extent to a new mft
1440        // record or by starting a new extent in a new mft record or by
1441        // moving other attributes out of this mft record.
1442        // Note: It will need to be a special mft record and if none of
1443        // those are available it gets rather complicated...
1444        ntfs_error(vol->sb, "Not enough space in this mft record to "
1445                "accommodate extended mft bitmap attribute "
1446                "extent. Cannot handle this yet.");
1447        ret = -EOPNOTSUPP;
1448        goto undo_alloc;
1449    }
1450    status.mp_rebuilt = 1;
1451    /* Generate the mapping pairs array directly into the attr record. */
1452    ret = ntfs_mapping_pairs_build(vol, (u8*)a +
1453            le16_to_cpu(a->data.non_resident.mapping_pairs_offset),
1454            mp_size, rl2, ll, -1, NULL);
1455    if (unlikely(ret)) {
1456        ntfs_error(vol->sb, "Failed to build mapping pairs array for "
1457                "mft bitmap attribute.");
1458        goto undo_alloc;
1459    }
1460    /* Update the highest_vcn. */
1461    a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 1);
1462    /*
1463     * We now have extended the mft bitmap allocated_size by one cluster.
1464     * Reflect this in the ntfs_inode structure and the attribute record.
1465     */
1466    if (a->data.non_resident.lowest_vcn) {
1467        /*
1468         * We are not in the first attribute extent, switch to it, but
1469         * first ensure the changes will make it to disk later.
1470         */
1471        flush_dcache_mft_record_page(ctx->ntfs_ino);
1472        mark_mft_record_dirty(ctx->ntfs_ino);
1473        ntfs_attr_reinit_search_ctx(ctx);
1474        ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
1475                mftbmp_ni->name_len, CASE_SENSITIVE, 0, NULL,
1476                0, ctx);
1477        if (unlikely(ret)) {
1478            ntfs_error(vol->sb, "Failed to find first attribute "
1479                    "extent of mft bitmap attribute.");
1480            goto restore_undo_alloc;
1481        }
1482        a = ctx->attr;
1483    }
1484    write_lock_irqsave(&mftbmp_ni->size_lock, flags);
1485    mftbmp_ni->allocated_size += vol->cluster_size;
1486    a->data.non_resident.allocated_size =
1487            cpu_to_sle64(mftbmp_ni->allocated_size);
1488    write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
1489    /* Ensure the changes make it to disk. */
1490    flush_dcache_mft_record_page(ctx->ntfs_ino);
1491    mark_mft_record_dirty(ctx->ntfs_ino);
1492    ntfs_attr_put_search_ctx(ctx);
1493    unmap_mft_record(mft_ni);
1494    up_write(&mftbmp_ni->runlist.lock);
1495    ntfs_debug("Done.");
1496    return 0;
1497restore_undo_alloc:
1498    ntfs_attr_reinit_search_ctx(ctx);
1499    if (ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
1500            mftbmp_ni->name_len, CASE_SENSITIVE, rl[1].vcn, NULL,
1501            0, ctx)) {
1502        ntfs_error(vol->sb, "Failed to find last attribute extent of "
1503                "mft bitmap attribute.%s", es);
1504        write_lock_irqsave(&mftbmp_ni->size_lock, flags);
1505        mftbmp_ni->allocated_size += vol->cluster_size;
1506        write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
1507        ntfs_attr_put_search_ctx(ctx);
1508        unmap_mft_record(mft_ni);
1509        up_write(&mftbmp_ni->runlist.lock);
1510        /*
1511         * The only thing that is now wrong is ->allocated_size of the
1512         * base attribute extent which chkdsk should be able to fix.
1513         */
1514        NVolSetErrors(vol);
1515        return ret;
1516    }
1517    a = ctx->attr;
1518    a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 2);
1519undo_alloc:
1520    if (status.added_cluster) {
1521        /* Truncate the last run in the runlist by one cluster. */
1522        rl->length--;
1523        rl[1].vcn--;
1524    } else if (status.added_run) {
1525        lcn = rl->lcn;
1526        /* Remove the last run from the runlist. */
1527        rl->lcn = rl[1].lcn;
1528        rl->length = 0;
1529    }
1530    /* Deallocate the cluster. */
1531    down_write(&vol->lcnbmp_lock);
1532    if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
1533        ntfs_error(vol->sb, "Failed to free allocated cluster.%s", es);
1534        NVolSetErrors(vol);
1535    }
1536    up_write(&vol->lcnbmp_lock);
1537    if (status.mp_rebuilt) {
1538        if (ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
1539                a->data.non_resident.mapping_pairs_offset),
1540                old_alen - le16_to_cpu(
1541                a->data.non_resident.mapping_pairs_offset),
1542                rl2, ll, -1, NULL)) {
1543            ntfs_error(vol->sb, "Failed to restore mapping pairs "
1544                    "array.%s", es);
1545            NVolSetErrors(vol);
1546        }
1547        if (ntfs_attr_record_resize(ctx->mrec, a, old_alen)) {
1548            ntfs_error(vol->sb, "Failed to restore attribute "
1549                    "record.%s", es);
1550            NVolSetErrors(vol);
1551        }
1552        flush_dcache_mft_record_page(ctx->ntfs_ino);
1553        mark_mft_record_dirty(ctx->ntfs_ino);
1554    }
1555    if (ctx)
1556        ntfs_attr_put_search_ctx(ctx);
1557    if (!IS_ERR(mrec))
1558        unmap_mft_record(mft_ni);
1559    up_write(&mftbmp_ni->runlist.lock);
1560    return ret;
1561}
1562
1563/**
1564 * ntfs_mft_bitmap_extend_initialized_nolock - extend mftbmp initialized data
1565 * @vol: volume on which to extend the mft bitmap attribute
1566 *
1567 * Extend the initialized portion of the mft bitmap attribute on the ntfs
1568 * volume @vol by 8 bytes.
1569 *
1570 * Note: Only changes initialized_size and data_size, i.e. requires that
1571 * allocated_size is big enough to fit the new initialized_size.
1572 *
1573 * Return 0 on success and -error on error.
1574 *
1575 * Locking: Caller must hold vol->mftbmp_lock for writing.
1576 */
1577static int ntfs_mft_bitmap_extend_initialized_nolock(ntfs_volume *vol)
1578{
1579    s64 old_data_size, old_initialized_size;
1580    unsigned long flags;
1581    struct inode *mftbmp_vi;
1582    ntfs_inode *mft_ni, *mftbmp_ni;
1583    ntfs_attr_search_ctx *ctx;
1584    MFT_RECORD *mrec;
1585    ATTR_RECORD *a;
1586    int ret;
1587
1588    ntfs_debug("Extending mft bitmap initiailized (and data) size.");
1589    mft_ni = NTFS_I(vol->mft_ino);
1590    mftbmp_vi = vol->mftbmp_ino;
1591    mftbmp_ni = NTFS_I(mftbmp_vi);
1592    /* Get the attribute record. */
1593    mrec = map_mft_record(mft_ni);
1594    if (IS_ERR(mrec)) {
1595        ntfs_error(vol->sb, "Failed to map mft record.");
1596        return PTR_ERR(mrec);
1597    }
1598    ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
1599    if (unlikely(!ctx)) {
1600        ntfs_error(vol->sb, "Failed to get search context.");
1601        ret = -ENOMEM;
1602        goto unm_err_out;
1603    }
1604    ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
1605            mftbmp_ni->name_len, CASE_SENSITIVE, 0, NULL, 0, ctx);
1606    if (unlikely(ret)) {
1607        ntfs_error(vol->sb, "Failed to find first attribute extent of "
1608                "mft bitmap attribute.");
1609        if (ret == -ENOENT)
1610            ret = -EIO;
1611        goto put_err_out;
1612    }
1613    a = ctx->attr;
1614    write_lock_irqsave(&mftbmp_ni->size_lock, flags);
1615    old_data_size = i_size_read(mftbmp_vi);
1616    old_initialized_size = mftbmp_ni->initialized_size;
1617    /*
1618     * We can simply update the initialized_size before filling the space
1619     * with zeroes because the caller is holding the mft bitmap lock for
1620     * writing which ensures that no one else is trying to access the data.
1621     */
1622    mftbmp_ni->initialized_size += 8;
1623    a->data.non_resident.initialized_size =
1624            cpu_to_sle64(mftbmp_ni->initialized_size);
1625    if (mftbmp_ni->initialized_size > old_data_size) {
1626        i_size_write(mftbmp_vi, mftbmp_ni->initialized_size);
1627        a->data.non_resident.data_size =
1628                cpu_to_sle64(mftbmp_ni->initialized_size);
1629    }
1630    write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
1631    /* Ensure the changes make it to disk. */
1632    flush_dcache_mft_record_page(ctx->ntfs_ino);
1633    mark_mft_record_dirty(ctx->ntfs_ino);
1634    ntfs_attr_put_search_ctx(ctx);
1635    unmap_mft_record(mft_ni);
1636    /* Initialize the mft bitmap attribute value with zeroes. */
1637    ret = ntfs_attr_set(mftbmp_ni, old_initialized_size, 8, 0);
1638    if (likely(!ret)) {
1639        ntfs_debug("Done. (Wrote eight initialized bytes to mft "
1640                "bitmap.");
1641        return 0;
1642    }
1643    ntfs_error(vol->sb, "Failed to write to mft bitmap.");
1644    /* Try to recover from the error. */
1645    mrec = map_mft_record(mft_ni);
1646    if (IS_ERR(mrec)) {
1647        ntfs_error(vol->sb, "Failed to map mft record.%s", es);
1648        NVolSetErrors(vol);
1649        return ret;
1650    }
1651    ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
1652    if (unlikely(!ctx)) {
1653        ntfs_error(vol->sb, "Failed to get search context.%s", es);
1654        NVolSetErrors(vol);
1655        goto unm_err_out;
1656    }
1657    if (ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
1658            mftbmp_ni->name_len, CASE_SENSITIVE, 0, NULL, 0, ctx)) {
1659        ntfs_error(vol->sb, "Failed to find first attribute extent of "
1660                "mft bitmap attribute.%s", es);
1661        NVolSetErrors(vol);
1662put_err_out:
1663        ntfs_attr_put_search_ctx(ctx);
1664unm_err_out:
1665        unmap_mft_record(mft_ni);
1666        goto err_out;
1667    }
1668    a = ctx->attr;
1669    write_lock_irqsave(&mftbmp_ni->size_lock, flags);
1670    mftbmp_ni->initialized_size = old_initialized_size;
1671    a->data.non_resident.initialized_size =
1672            cpu_to_sle64(old_initialized_size);
1673    if (i_size_read(mftbmp_vi) != old_data_size) {
1674        i_size_write(mftbmp_vi, old_data_size);
1675        a->data.non_resident.data_size = cpu_to_sle64(old_data_size);
1676    }
1677    write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
1678    flush_dcache_mft_record_page(ctx->ntfs_ino);
1679    mark_mft_record_dirty(ctx->ntfs_ino);
1680    ntfs_attr_put_search_ctx(ctx);
1681    unmap_mft_record(mft_ni);
1682#ifdef DEBUG
1683    read_lock_irqsave(&mftbmp_ni->size_lock, flags);
1684    ntfs_debug("Restored status of mftbmp: allocated_size 0x%llx, "
1685            "data_size 0x%llx, initialized_size 0x%llx.",
1686            (long long)mftbmp_ni->allocated_size,
1687            (long long)i_size_read(mftbmp_vi),
1688            (long long)mftbmp_ni->initialized_size);
1689    read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
1690#endif /* DEBUG */
1691err_out:
1692    return ret;
1693}
1694
1695/**
1696 * ntfs_mft_data_extend_allocation_nolock - extend mft data attribute
1697 * @vol: volume on which to extend the mft data attribute
1698 *
1699 * Extend the mft data attribute on the ntfs volume @vol by 16 mft records
1700 * worth of clusters or if not enough space for this by one mft record worth
1701 * of clusters.
1702 *
1703 * Note: Only changes allocated_size, i.e. does not touch initialized_size or
1704 * data_size.
1705 *
1706 * Return 0 on success and -errno on error.
1707 *
1708 * Locking: - Caller must hold vol->mftbmp_lock for writing.
1709 * - This function takes NTFS_I(vol->mft_ino)->runlist.lock for
1710 * writing and releases it before returning.
1711 * - This function calls functions which take vol->lcnbmp_lock for
1712 * writing and release it before returning.
1713 */
1714static int ntfs_mft_data_extend_allocation_nolock(ntfs_volume *vol)
1715{
1716    LCN lcn;
1717    VCN old_last_vcn;
1718    s64 min_nr, nr, ll;
1719    unsigned long flags;
1720    ntfs_inode *mft_ni;
1721    runlist_element *rl, *rl2;
1722    ntfs_attr_search_ctx *ctx = NULL;
1723    MFT_RECORD *mrec;
1724    ATTR_RECORD *a = NULL;
1725    int ret, mp_size;
1726    u32 old_alen = 0;
1727    bool mp_rebuilt = false;
1728
1729    ntfs_debug("Extending mft data allocation.");
1730    mft_ni = NTFS_I(vol->mft_ino);
1731    /*
1732     * Determine the preferred allocation location, i.e. the last lcn of
1733     * the mft data attribute. The allocated size of the mft data
1734     * attribute cannot be zero so we are ok to do this.
1735     */
1736    down_write(&mft_ni->runlist.lock);
1737    read_lock_irqsave(&mft_ni->size_lock, flags);
1738    ll = mft_ni->allocated_size;
1739    read_unlock_irqrestore(&mft_ni->size_lock, flags);
1740    rl = ntfs_attr_find_vcn_nolock(mft_ni,
1741            (ll - 1) >> vol->cluster_size_bits, NULL);
1742    if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
1743        up_write(&mft_ni->runlist.lock);
1744        ntfs_error(vol->sb, "Failed to determine last allocated "
1745                "cluster of mft data attribute.");
1746        if (!IS_ERR(rl))
1747            ret = -EIO;
1748        else
1749            ret = PTR_ERR(rl);
1750        return ret;
1751    }
1752    lcn = rl->lcn + rl->length;
1753    ntfs_debug("Last lcn of mft data attribute is 0x%llx.", (long long)lcn);
1754    /* Minimum allocation is one mft record worth of clusters. */
1755    min_nr = vol->mft_record_size >> vol->cluster_size_bits;
1756    if (!min_nr)
1757        min_nr = 1;
1758    /* Want to allocate 16 mft records worth of clusters. */
1759    nr = vol->mft_record_size << 4 >> vol->cluster_size_bits;
1760    if (!nr)
1761        nr = min_nr;
1762    /* Ensure we do not go above 2^32-1 mft records. */
1763    read_lock_irqsave(&mft_ni->size_lock, flags);
1764    ll = mft_ni->allocated_size;
1765    read_unlock_irqrestore(&mft_ni->size_lock, flags);
1766    if (unlikely((ll + (nr << vol->cluster_size_bits)) >>
1767            vol->mft_record_size_bits >= (1ll << 32))) {
1768        nr = min_nr;
1769        if (unlikely((ll + (nr << vol->cluster_size_bits)) >>
1770                vol->mft_record_size_bits >= (1ll << 32))) {
1771            ntfs_warning(vol->sb, "Cannot allocate mft record "
1772                    "because the maximum number of inodes "
1773                    "(2^32) has already been reached.");
1774            up_write(&mft_ni->runlist.lock);
1775            return -ENOSPC;
1776        }
1777    }
1778    ntfs_debug("Trying mft data allocation with %s cluster count %lli.",
1779            nr > min_nr ? "default" : "minimal", (long long)nr);
1780    old_last_vcn = rl[1].vcn;
1781    do {
1782        rl2 = ntfs_cluster_alloc(vol, old_last_vcn, nr, lcn, MFT_ZONE,
1783                true);
1784        if (likely(!IS_ERR(rl2)))
1785            break;
1786        if (PTR_ERR(rl2) != -ENOSPC || nr == min_nr) {
1787            ntfs_error(vol->sb, "Failed to allocate the minimal "
1788                    "number of clusters (%lli) for the "
1789                    "mft data attribute.", (long long)nr);
1790            up_write(&mft_ni->runlist.lock);
1791            return PTR_ERR(rl2);
1792        }
1793        /*
1794         * There is not enough space to do the allocation, but there
1795         * might be enough space to do a minimal allocation so try that
1796         * before failing.
1797         */
1798        nr = min_nr;
1799        ntfs_debug("Retrying mft data allocation with minimal cluster "
1800                "count %lli.", (long long)nr);
1801    } while (1);
1802    rl = ntfs_runlists_merge(mft_ni->runlist.rl, rl2);
1803    if (IS_ERR(rl)) {
1804        up_write(&mft_ni->runlist.lock);
1805        ntfs_error(vol->sb, "Failed to merge runlists for mft data "
1806                "attribute.");
1807        if (ntfs_cluster_free_from_rl(vol, rl2)) {
1808            ntfs_error(vol->sb, "Failed to dealocate clusters "
1809                    "from the mft data attribute.%s", es);
1810            NVolSetErrors(vol);
1811        }
1812        ntfs_free(rl2);
1813        return PTR_ERR(rl);
1814    }
1815    mft_ni->runlist.rl = rl;
1816    ntfs_debug("Allocated %lli clusters.", (long long)nr);
1817    /* Find the last run in the new runlist. */
1818    for (; rl[1].length; rl++)
1819        ;
1820    /* Update the attribute record as well. */
1821    mrec = map_mft_record(mft_ni);
1822    if (IS_ERR(mrec)) {
1823        ntfs_error(vol->sb, "Failed to map mft record.");
1824        ret = PTR_ERR(mrec);
1825        goto undo_alloc;
1826    }
1827    ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
1828    if (unlikely(!ctx)) {
1829        ntfs_error(vol->sb, "Failed to get search context.");
1830        ret = -ENOMEM;
1831        goto undo_alloc;
1832    }
1833    ret = ntfs_attr_lookup(mft_ni->type, mft_ni->name, mft_ni->name_len,
1834            CASE_SENSITIVE, rl[1].vcn, NULL, 0, ctx);
1835    if (unlikely(ret)) {
1836        ntfs_error(vol->sb, "Failed to find last attribute extent of "
1837                "mft data attribute.");
1838        if (ret == -ENOENT)
1839            ret = -EIO;
1840        goto undo_alloc;
1841    }
1842    a = ctx->attr;
1843    ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
1844    /* Search back for the previous last allocated cluster of mft bitmap. */
1845    for (rl2 = rl; rl2 > mft_ni->runlist.rl; rl2--) {
1846        if (ll >= rl2->vcn)
1847            break;
1848    }
1849    BUG_ON(ll < rl2->vcn);
1850    BUG_ON(ll >= rl2->vcn + rl2->length);
1851    /* Get the size for the new mapping pairs array for this extent. */
1852    mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll, -1);
1853    if (unlikely(mp_size <= 0)) {
1854        ntfs_error(vol->sb, "Get size for mapping pairs failed for "
1855                "mft data attribute extent.");
1856        ret = mp_size;
1857        if (!ret)
1858            ret = -EIO;
1859        goto undo_alloc;
1860    }
1861    /* Expand the attribute record if necessary. */
1862    old_alen = le32_to_cpu(a->length);
1863    ret = ntfs_attr_record_resize(ctx->mrec, a, mp_size +
1864            le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
1865    if (unlikely(ret)) {
1866        if (ret != -ENOSPC) {
1867            ntfs_error(vol->sb, "Failed to resize attribute "
1868                    "record for mft data attribute.");
1869            goto undo_alloc;
1870        }
1871        // TODO: Deal with this by moving this extent to a new mft
1872        // record or by starting a new extent in a new mft record or by
1873        // moving other attributes out of this mft record.
1874        // Note: Use the special reserved mft records and ensure that
1875        // this extent is not required to find the mft record in
1876        // question. If no free special records left we would need to
1877        // move an existing record away, insert ours in its place, and
1878        // then place the moved record into the newly allocated space
1879        // and we would then need to update all references to this mft
1880        // record appropriately. This is rather complicated...
1881        ntfs_error(vol->sb, "Not enough space in this mft record to "
1882                "accommodate extended mft data attribute "
1883                "extent. Cannot handle this yet.");
1884        ret = -EOPNOTSUPP;
1885        goto undo_alloc;
1886    }
1887    mp_rebuilt = true;
1888    /* Generate the mapping pairs array directly into the attr record. */
1889    ret = ntfs_mapping_pairs_build(vol, (u8*)a +
1890            le16_to_cpu(a->data.non_resident.mapping_pairs_offset),
1891            mp_size, rl2, ll, -1, NULL);
1892    if (unlikely(ret)) {
1893        ntfs_error(vol->sb, "Failed to build mapping pairs array of "
1894                "mft data attribute.");
1895        goto undo_alloc;
1896    }
1897    /* Update the highest_vcn. */
1898    a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 1);
1899    /*
1900     * We now have extended the mft data allocated_size by nr clusters.
1901     * Reflect this in the ntfs_inode structure and the attribute record.
1902     * @rl is the last (non-terminator) runlist element of mft data
1903     * attribute.
1904     */
1905    if (a->data.non_resident.lowest_vcn) {
1906        /*
1907         * We are not in the first attribute extent, switch to it, but
1908         * first ensure the changes will make it to disk later.
1909         */
1910        flush_dcache_mft_record_page(ctx->ntfs_ino);
1911        mark_mft_record_dirty(ctx->ntfs_ino);
1912        ntfs_attr_reinit_search_ctx(ctx);
1913        ret = ntfs_attr_lookup(mft_ni->type, mft_ni->name,
1914                mft_ni->name_len, CASE_SENSITIVE, 0, NULL, 0,
1915                ctx);
1916        if (unlikely(ret)) {
1917            ntfs_error(vol->sb, "Failed to find first attribute "
1918                    "extent of mft data attribute.");
1919            goto restore_undo_alloc;
1920        }
1921        a = ctx->attr;
1922    }
1923    write_lock_irqsave(&mft_ni->size_lock, flags);
1924    mft_ni->allocated_size += nr << vol->cluster_size_bits;
1925    a->data.non_resident.allocated_size =
1926            cpu_to_sle64(mft_ni->allocated_size);
1927    write_unlock_irqrestore(&mft_ni->size_lock, flags);
1928    /* Ensure the changes make it to disk. */
1929    flush_dcache_mft_record_page(ctx->ntfs_ino);
1930    mark_mft_record_dirty(ctx->ntfs_ino);
1931    ntfs_attr_put_search_ctx(ctx);
1932    unmap_mft_record(mft_ni);
1933    up_write(&mft_ni->runlist.lock);
1934    ntfs_debug("Done.");
1935    return 0;
1936restore_undo_alloc:
1937    ntfs_attr_reinit_search_ctx(ctx);
1938    if (ntfs_attr_lookup(mft_ni->type, mft_ni->name, mft_ni->name_len,
1939            CASE_SENSITIVE, rl[1].vcn, NULL, 0, ctx)) {
1940        ntfs_error(vol->sb, "Failed to find last attribute extent of "
1941                "mft data attribute.%s", es);
1942        write_lock_irqsave(&mft_ni->size_lock, flags);
1943        mft_ni->allocated_size += nr << vol->cluster_size_bits;
1944        write_unlock_irqrestore(&mft_ni->size_lock, flags);
1945        ntfs_attr_put_search_ctx(ctx);
1946        unmap_mft_record(mft_ni);
1947        up_write(&mft_ni->runlist.lock);
1948        /*
1949         * The only thing that is now wrong is ->allocated_size of the
1950         * base attribute extent which chkdsk should be able to fix.
1951         */
1952        NVolSetErrors(vol);
1953        return ret;
1954    }
1955    ctx->attr->data.non_resident.highest_vcn =
1956            cpu_to_sle64(old_last_vcn - 1);
1957undo_alloc:
1958    if (ntfs_cluster_free(mft_ni, old_last_vcn, -1, ctx) < 0) {
1959        ntfs_error(vol->sb, "Failed to free clusters from mft data "
1960                "attribute.%s", es);
1961        NVolSetErrors(vol);
1962    }
1963    a = ctx->attr;
1964    if (ntfs_rl_truncate_nolock(vol, &mft_ni->runlist, old_last_vcn)) {
1965        ntfs_error(vol->sb, "Failed to truncate mft data attribute "
1966                "runlist.%s", es);
1967        NVolSetErrors(vol);
1968    }
1969    if (mp_rebuilt && !IS_ERR(ctx->mrec)) {
1970        if (ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
1971                a->data.non_resident.mapping_pairs_offset),
1972                old_alen - le16_to_cpu(
1973                a->data.non_resident.mapping_pairs_offset),
1974                rl2, ll, -1, NULL)) {
1975            ntfs_error(vol->sb, "Failed to restore mapping pairs "
1976                    "array.%s", es);
1977            NVolSetErrors(vol);
1978        }
1979        if (ntfs_attr_record_resize(ctx->mrec, a, old_alen)) {
1980            ntfs_error(vol->sb, "Failed to restore attribute "
1981                    "record.%s", es);
1982            NVolSetErrors(vol);
1983        }
1984        flush_dcache_mft_record_page(ctx->ntfs_ino);
1985        mark_mft_record_dirty(ctx->ntfs_ino);
1986    } else if (IS_ERR(ctx->mrec)) {
1987        ntfs_error(vol->sb, "Failed to restore attribute search "
1988                "context.%s", es);
1989        NVolSetErrors(vol);
1990    }
1991    if (ctx)
1992        ntfs_attr_put_search_ctx(ctx);
1993    if (!IS_ERR(mrec))
1994        unmap_mft_record(mft_ni);
1995    up_write(&mft_ni->runlist.lock);
1996    return ret;
1997}
1998
1999/**
2000 * ntfs_mft_record_layout - layout an mft record into a memory buffer
2001 * @vol: volume to which the mft record will belong
2002 * @mft_no: mft reference specifying the mft record number
2003 * @m: destination buffer of size >= @vol->mft_record_size bytes
2004 *
2005 * Layout an empty, unused mft record with the mft record number @mft_no into
2006 * the buffer @m. The volume @vol is needed because the mft record structure
2007 * was modified in NTFS 3.1 so we need to know which volume version this mft
2008 * record will be used on.
2009 *
2010 * Return 0 on success and -errno on error.
2011 */
2012static int ntfs_mft_record_layout(const ntfs_volume *vol, const s64 mft_no,
2013        MFT_RECORD *m)
2014{
2015    ATTR_RECORD *a;
2016
2017    ntfs_debug("Entering for mft record 0x%llx.", (long long)mft_no);
2018    if (mft_no >= (1ll << 32)) {
2019        ntfs_error(vol->sb, "Mft record number 0x%llx exceeds "
2020                "maximum of 2^32.", (long long)mft_no);
2021        return -ERANGE;
2022    }
2023    /* Start by clearing the whole mft record to gives us a clean slate. */
2024    memset(m, 0, vol->mft_record_size);
2025    /* Aligned to 2-byte boundary. */
2026    if (vol->major_ver < 3 || (vol->major_ver == 3 && !vol->minor_ver))
2027        m->usa_ofs = cpu_to_le16((sizeof(MFT_RECORD_OLD) + 1) & ~1);
2028    else {
2029        m->usa_ofs = cpu_to_le16((sizeof(MFT_RECORD) + 1) & ~1);
2030        /*
2031         * Set the NTFS 3.1+ specific fields while we know that the
2032         * volume version is 3.1+.
2033         */
2034        m->reserved = 0;
2035        m->mft_record_number = cpu_to_le32((u32)mft_no);
2036    }
2037    m->magic = magic_FILE;
2038    if (vol->mft_record_size >= NTFS_BLOCK_SIZE)
2039        m->usa_count = cpu_to_le16(vol->mft_record_size /
2040                NTFS_BLOCK_SIZE + 1);
2041    else {
2042        m->usa_count = cpu_to_le16(1);
2043        ntfs_warning(vol->sb, "Sector size is bigger than mft record "
2044                "size. Setting usa_count to 1. If chkdsk "
2045                "reports this as corruption, please email "
2046                "linux-ntfs-dev@lists.sourceforge.net stating "
2047                "that you saw this message and that the "
2048                "modified filesystem created was corrupt. "
2049                "Thank you.");
2050    }
2051    /* Set the update sequence number to 1. */
2052    *(le16*)((u8*)m + le16_to_cpu(m->usa_ofs)) = cpu_to_le16(1);
2053    m->lsn = 0;
2054    m->sequence_number = cpu_to_le16(1);
2055    m->link_count = 0;
2056    /*
2057     * Place the attributes straight after the update sequence array,
2058     * aligned to 8-byte boundary.
2059     */
2060    m->attrs_offset = cpu_to_le16((le16_to_cpu(m->usa_ofs) +
2061            (le16_to_cpu(m->usa_count) << 1) + 7) & ~7);
2062    m->flags = 0;
2063    /*
2064     * Using attrs_offset plus eight bytes (for the termination attribute).
2065     * attrs_offset is already aligned to 8-byte boundary, so no need to
2066     * align again.
2067     */
2068    m->bytes_in_use = cpu_to_le32(le16_to_cpu(m->attrs_offset) + 8);
2069    m->bytes_allocated = cpu_to_le32(vol->mft_record_size);
2070    m->base_mft_record = 0;
2071    m->next_attr_instance = 0;
2072    /* Add the termination attribute. */
2073    a = (ATTR_RECORD*)((u8*)m + le16_to_cpu(m->attrs_offset));
2074    a->type = AT_END;
2075    a->length = 0;
2076    ntfs_debug("Done.");
2077    return 0;
2078}
2079
2080/**
2081 * ntfs_mft_record_format - format an mft record on an ntfs volume
2082 * @vol: volume on which to format the mft record
2083 * @mft_no: mft record number to format
2084 *
2085 * Format the mft record @mft_no in $MFT/$DATA, i.e. lay out an empty, unused
2086 * mft record into the appropriate place of the mft data attribute. This is
2087 * used when extending the mft data attribute.
2088 *
2089 * Return 0 on success and -errno on error.
2090 */
2091static int ntfs_mft_record_format(const ntfs_volume *vol, const s64 mft_no)
2092{
2093    loff_t i_size;
2094    struct inode *mft_vi = vol->mft_ino;
2095    struct page *page;
2096    MFT_RECORD *m;
2097    pgoff_t index, end_index;
2098    unsigned int ofs;
2099    int err;
2100
2101    ntfs_debug("Entering for mft record 0x%llx.", (long long)mft_no);
2102    /*
2103     * The index into the page cache and the offset within the page cache
2104     * page of the wanted mft record.
2105     */
2106    index = mft_no << vol->mft_record_size_bits >> PAGE_CACHE_SHIFT;
2107    ofs = (mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
2108    /* The maximum valid index into the page cache for $MFT's data. */
2109    i_size = i_size_read(mft_vi);
2110    end_index = i_size >> PAGE_CACHE_SHIFT;
2111    if (unlikely(index >= end_index)) {
2112        if (unlikely(index > end_index || ofs + vol->mft_record_size >=
2113                (i_size & ~PAGE_CACHE_MASK))) {
2114            ntfs_error(vol->sb, "Tried to format non-existing mft "
2115                    "record 0x%llx.", (long long)mft_no);
2116            return -ENOENT;
2117        }
2118    }
2119    /* Read, map, and pin the page containing the mft record. */
2120    page = ntfs_map_page(mft_vi->i_mapping, index);
2121    if (IS_ERR(page)) {
2122        ntfs_error(vol->sb, "Failed to map page containing mft record "
2123                "to format 0x%llx.", (long long)mft_no);
2124        return PTR_ERR(page);
2125    }
2126    lock_page(page);
2127    BUG_ON(!PageUptodate(page));
2128    ClearPageUptodate(page);
2129    m = (MFT_RECORD*)((u8*)page_address(page) + ofs);
2130    err = ntfs_mft_record_layout(vol, mft_no, m);
2131    if (unlikely(err)) {
2132        ntfs_error(vol->sb, "Failed to layout mft record 0x%llx.",
2133                (long long)mft_no);
2134        SetPageUptodate(page);
2135        unlock_page(page);
2136        ntfs_unmap_page(page);
2137        return err;
2138    }
2139    flush_dcache_page(page);
2140    SetPageUptodate(page);
2141    unlock_page(page);
2142    /*
2143     * Make sure the mft record is written out to disk. We could use
2144     * ilookup5() to check if an inode is in icache and so on but this is
2145     * unnecessary as ntfs_writepage() will write the dirty record anyway.
2146     */
2147    mark_ntfs_record_dirty(page, ofs);
2148    ntfs_unmap_page(page);
2149    ntfs_debug("Done.");
2150    return 0;
2151}
2152
2153/**
2154 * ntfs_mft_record_alloc - allocate an mft record on an ntfs volume
2155 * @vol: [IN] volume on which to allocate the mft record
2156 * @mode: [IN] mode if want a file or directory, i.e. base inode or 0
2157 * @base_ni: [IN] open base inode if allocating an extent mft record or NULL
2158 * @mrec: [OUT] on successful return this is the mapped mft record
2159 *
2160 * Allocate an mft record in $MFT/$DATA of an open ntfs volume @vol.
2161 *
2162 * If @base_ni is NULL make the mft record a base mft record, i.e. a file or
2163 * direvctory inode, and allocate it at the default allocator position. In
2164 * this case @mode is the file mode as given to us by the caller. We in
2165 * particular use @mode to distinguish whether a file or a directory is being
2166 * created (S_IFDIR(mode) and S_IFREG(mode), respectively).
2167 *
2168 * If @base_ni is not NULL make the allocated mft record an extent record,
2169 * allocate it starting at the mft record after the base mft record and attach
2170 * the allocated and opened ntfs inode to the base inode @base_ni. In this
2171 * case @mode must be 0 as it is meaningless for extent inodes.
2172 *
2173 * You need to check the return value with IS_ERR(). If false, the function
2174 * was successful and the return value is the now opened ntfs inode of the
2175 * allocated mft record. *@mrec is then set to the allocated, mapped, pinned,
2176 * and locked mft record. If IS_ERR() is true, the function failed and the
2177 * error code is obtained from PTR_ERR(return value). *@mrec is undefined in
2178 * this case.
2179 *
2180 * Allocation strategy:
2181 *
2182 * To find a free mft record, we scan the mft bitmap for a zero bit. To
2183 * optimize this we start scanning at the place specified by @base_ni or if
2184 * @base_ni is NULL we start where we last stopped and we perform wrap around
2185 * when we reach the end. Note, we do not try to allocate mft records below
2186 * number 24 because numbers 0 to 15 are the defined system files anyway and 16
2187 * to 24 are special in that they are used for storing extension mft records
2188 * for the $DATA attribute of $MFT. This is required to avoid the possibility
2189 * of creating a runlist with a circular dependency which once written to disk
2190 * can never be read in again. Windows will only use records 16 to 24 for
2191 * normal files if the volume is completely out of space. We never use them
2192 * which means that when the volume is really out of space we cannot create any
2193 * more files while Windows can still create up to 8 small files. We can start
2194 * doing this at some later time, it does not matter much for now.
2195 *
2196 * When scanning the mft bitmap, we only search up to the last allocated mft
2197 * record. If there are no free records left in the range 24 to number of
2198 * allocated mft records, then we extend the $MFT/$DATA attribute in order to
2199 * create free mft records. We extend the allocated size of $MFT/$DATA by 16
2200 * records at a time or one cluster, if cluster size is above 16kiB. If there
2201 * is not sufficient space to do this, we try to extend by a single mft record
2202 * or one cluster, if cluster size is above the mft record size.
2203 *
2204 * No matter how many mft records we allocate, we initialize only the first
2205 * allocated mft record, incrementing mft data size and initialized size
2206 * accordingly, open an ntfs_inode for it and return it to the caller, unless
2207 * there are less than 24 mft records, in which case we allocate and initialize
2208 * mft records until we reach record 24 which we consider as the first free mft
2209 * record for use by normal files.
2210 *
2211 * If during any stage we overflow the initialized data in the mft bitmap, we
2212 * extend the initialized size (and data size) by 8 bytes, allocating another
2213 * cluster if required. The bitmap data size has to be at least equal to the
2214 * number of mft records in the mft, but it can be bigger, in which case the
2215 * superflous bits are padded with zeroes.
2216 *
2217 * Thus, when we return successfully (IS_ERR() is false), we will have:
2218 * - initialized / extended the mft bitmap if necessary,
2219 * - initialized / extended the mft data if necessary,
2220 * - set the bit corresponding to the mft record being allocated in the
2221 * mft bitmap,
2222 * - opened an ntfs_inode for the allocated mft record, and we will have
2223 * - returned the ntfs_inode as well as the allocated mapped, pinned, and
2224 * locked mft record.
2225 *
2226 * On error, the volume will be left in a consistent state and no record will
2227 * be allocated. If rolling back a partial operation fails, we may leave some
2228 * inconsistent metadata in which case we set NVolErrors() so the volume is
2229 * left dirty when unmounted.
2230 *
2231 * Note, this function cannot make use of most of the normal functions, like
2232 * for example for attribute resizing, etc, because when the run list overflows
2233 * the base mft record and an attribute list is used, it is very important that
2234 * the extension mft records used to store the $DATA attribute of $MFT can be
2235 * reached without having to read the information contained inside them, as
2236 * this would make it impossible to find them in the first place after the
2237 * volume is unmounted. $MFT/$BITMAP probably does not need to follow this
2238 * rule because the bitmap is not essential for finding the mft records, but on
2239 * the other hand, handling the bitmap in this special way would make life
2240 * easier because otherwise there might be circular invocations of functions
2241 * when reading the bitmap.
2242 */
2243ntfs_inode *ntfs_mft_record_alloc(ntfs_volume *vol, const int mode,
2244        ntfs_inode *base_ni, MFT_RECORD **mrec)
2245{
2246    s64 ll, bit, old_data_initialized, old_data_size;
2247    unsigned long flags;
2248    struct inode *vi;
2249    struct page *page;
2250    ntfs_inode *mft_ni, *mftbmp_ni, *ni;
2251    ntfs_attr_search_ctx *ctx;
2252    MFT_RECORD *m;
2253    ATTR_RECORD *a;
2254    pgoff_t index;
2255    unsigned int ofs;
2256    int err;
2257    le16 seq_no, usn;
2258    bool record_formatted = false;
2259
2260    if (base_ni) {
2261        ntfs_debug("Entering (allocating an extent mft record for "
2262                "base mft record 0x%llx).",
2263                (long long)base_ni->mft_no);
2264        /* @mode and @base_ni are mutually exclusive. */
2265        BUG_ON(mode);
2266    } else
2267        ntfs_debug("Entering (allocating a base mft record).");
2268    if (mode) {
2269        /* @mode and @base_ni are mutually exclusive. */
2270        BUG_ON(base_ni);
2271        /* We only support creation of normal files and directories. */
2272        if (!S_ISREG(mode) && !S_ISDIR(mode))
2273            return ERR_PTR(-EOPNOTSUPP);
2274    }
2275    BUG_ON(!mrec);
2276    mft_ni = NTFS_I(vol->mft_ino);
2277    mftbmp_ni = NTFS_I(vol->mftbmp_ino);
2278    down_write(&vol->mftbmp_lock);
2279    bit = ntfs_mft_bitmap_find_and_alloc_free_rec_nolock(vol, base_ni);
2280    if (bit >= 0) {
2281        ntfs_debug("Found and allocated free record (#1), bit 0x%llx.",
2282                (long long)bit);
2283        goto have_alloc_rec;
2284    }
2285    if (bit != -ENOSPC) {
2286        up_write(&vol->mftbmp_lock);
2287        return ERR_PTR(bit);
2288    }
2289    /*
2290     * No free mft records left. If the mft bitmap already covers more
2291     * than the currently used mft records, the next records are all free,
2292     * so we can simply allocate the first unused mft record.
2293     * Note: We also have to make sure that the mft bitmap at least covers
2294     * the first 24 mft records as they are special and whilst they may not
2295     * be in use, we do not allocate from them.
2296     */
2297    read_lock_irqsave(&mft_ni->size_lock, flags);
2298    ll = mft_ni->initialized_size >> vol->mft_record_size_bits;
2299    read_unlock_irqrestore(&mft_ni->size_lock, flags);
2300    read_lock_irqsave(&mftbmp_ni->size_lock, flags);
2301    old_data_initialized = mftbmp_ni->initialized_size;
2302    read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
2303    if (old_data_initialized << 3 > ll && old_data_initialized > 3) {
2304        bit = ll;
2305        if (bit < 24)
2306            bit = 24;
2307        if (unlikely(bit >= (1ll << 32)))
2308            goto max_err_out;
2309        ntfs_debug("Found free record (#2), bit 0x%llx.",
2310                (long long)bit);
2311        goto found_free_rec;
2312    }
2313    /*
2314     * The mft bitmap needs to be expanded until it covers the first unused
2315     * mft record that we can allocate.
2316     * Note: The smallest mft record we allocate is mft record 24.
2317     */
2318    bit = old_data_initialized << 3;
2319    if (unlikely(bit >= (1ll << 32)))
2320        goto max_err_out;
2321    read_lock_irqsave(&mftbmp_ni->size_lock, flags);
2322    old_data_size = mftbmp_ni->allocated_size;
2323    ntfs_debug("Status of mftbmp before extension: allocated_size 0x%llx, "
2324            "data_size 0x%llx, initialized_size 0x%llx.",
2325            (long long)old_data_size,
2326            (long long)i_size_read(vol->mftbmp_ino),
2327            (long long)old_data_initialized);
2328    read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
2329    if (old_data_initialized + 8 > old_data_size) {
2330        /* Need to extend bitmap by one more cluster. */
2331        ntfs_debug("mftbmp: initialized_size + 8 > allocated_size.");
2332        err = ntfs_mft_bitmap_extend_allocation_nolock(vol);
2333        if (unlikely(err)) {
2334            up_write(&vol->mftbmp_lock);
2335            goto err_out;
2336        }
2337#ifdef DEBUG
2338        read_lock_irqsave(&mftbmp_ni->size_lock, flags);
2339        ntfs_debug("Status of mftbmp after allocation extension: "
2340                "allocated_size 0x%llx, data_size 0x%llx, "
2341                "initialized_size 0x%llx.",
2342                (long long)mftbmp_ni->allocated_size,
2343                (long long)i_size_read(vol->mftbmp_ino),
2344                (long long)mftbmp_ni->initialized_size);
2345        read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
2346#endif /* DEBUG */
2347    }
2348    /*
2349     * We now have sufficient allocated space, extend the initialized_size
2350     * as well as the data_size if necessary and fill the new space with
2351     * zeroes.
2352     */
2353    err = ntfs_mft_bitmap_extend_initialized_nolock(vol);
2354    if (unlikely(err)) {
2355        up_write(&vol->mftbmp_lock);
2356        goto err_out;
2357    }
2358#ifdef DEBUG
2359    read_lock_irqsave(&mftbmp_ni->size_lock, flags);
2360    ntfs_debug("Status of mftbmp after initialized extension: "
2361            "allocated_size 0x%llx, data_size 0x%llx, "
2362            "initialized_size 0x%llx.",
2363            (long long)mftbmp_ni->allocated_size,
2364            (long long)i_size_read(vol->mftbmp_ino),
2365            (long long)mftbmp_ni->initialized_size);
2366    read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
2367#endif /* DEBUG */
2368    ntfs_debug("Found free record (#3), bit 0x%llx.", (long long)bit);
2369found_free_rec:
2370    /* @bit is the found free mft record, allocate it in the mft bitmap. */
2371    ntfs_debug("At found_free_rec.");
2372    err = ntfs_bitmap_set_bit(vol->mftbmp_ino, bit);
2373    if (unlikely(err)) {
2374        ntfs_error(vol->sb, "Failed to allocate bit in mft bitmap.");
2375        up_write(&vol->mftbmp_lock);
2376        goto err_out;
2377    }
2378    ntfs_debug("Set bit 0x%llx in mft bitmap.", (long long)bit);
2379have_alloc_rec:
2380    /*
2381     * The mft bitmap is now uptodate. Deal with mft data attribute now.
2382     * Note, we keep hold of the mft bitmap lock for writing until all
2383     * modifications to the mft data attribute are complete, too, as they
2384     * will impact decisions for mft bitmap and mft record allocation done
2385     * by a parallel allocation and if the lock is not maintained a
2386     * parallel allocation could allocate the same mft record as this one.
2387     */
2388    ll = (bit + 1) << vol->mft_record_size_bits;
2389    read_lock_irqsave(&mft_ni->size_lock, flags);
2390    old_data_initialized = mft_ni->initialized_size;
2391    read_unlock_irqrestore(&mft_ni->size_lock, flags);
2392    if (ll <= old_data_initialized) {
2393        ntfs_debug("Allocated mft record already initialized.");
2394        goto mft_rec_already_initialized;
2395    }
2396    ntfs_debug("Initializing allocated mft record.");
2397    /*
2398     * The mft record is outside the initialized data. Extend the mft data
2399     * attribute until it covers the allocated record. The loop is only
2400     * actually traversed more than once when a freshly formatted volume is
2401     * first written to so it optimizes away nicely in the common case.
2402     */
2403    read_lock_irqsave(&mft_ni->size_lock, flags);
2404    ntfs_debug("Status of mft data before extension: "
2405            "allocated_size 0x%llx, data_size 0x%llx, "
2406            "initialized_size 0x%llx.",
2407            (long long)mft_ni->allocated_size,
2408            (long long)i_size_read(vol->mft_ino),
2409            (long long)mft_ni->initialized_size);
2410    while (ll > mft_ni->allocated_size) {
2411        read_unlock_irqrestore(&mft_ni->size_lock, flags);
2412        err = ntfs_mft_data_extend_allocation_nolock(vol);
2413        if (unlikely(err)) {
2414            ntfs_error(vol->sb, "Failed to extend mft data "
2415                    "allocation.");
2416            goto undo_mftbmp_alloc_nolock;
2417        }
2418        read_lock_irqsave(&mft_ni->size_lock, flags);
2419        ntfs_debug("Status of mft data after allocation extension: "
2420                "allocated_size 0x%llx, data_size 0x%llx, "
2421                "initialized_size 0x%llx.",
2422                (long long)mft_ni->allocated_size,
2423                (long long)i_size_read(vol->mft_ino),
2424                (long long)mft_ni->initialized_size);
2425    }
2426    read_unlock_irqrestore(&mft_ni->size_lock, flags);
2427    /*
2428     * Extend mft data initialized size (and data size of course) to reach
2429     * the allocated mft record, formatting the mft records allong the way.
2430     * Note: We only modify the ntfs_inode structure as that is all that is
2431     * needed by ntfs_mft_record_format(). We will update the attribute
2432     * record itself in one fell swoop later on.
2433     */
2434    write_lock_irqsave(&mft_ni->size_lock, flags);
2435    old_data_initialized = mft_ni->initialized_size;
2436    old_data_size = vol->mft_ino->i_size;
2437    while (ll > mft_ni->initialized_size) {
2438        s64 new_initialized_size, mft_no;
2439        
2440        new_initialized_size = mft_ni->initialized_size +
2441                vol->mft_record_size;
2442        mft_no = mft_ni->initialized_size >> vol->mft_record_size_bits;
2443        if (new_initialized_size > i_size_read(vol->mft_ino))
2444            i_size_write(vol->mft_ino, new_initialized_size);
2445        write_unlock_irqrestore(&mft_ni->size_lock, flags);
2446        ntfs_debug("Initializing mft record 0x%llx.",
2447                (long long)mft_no);
2448        err = ntfs_mft_record_format(vol, mft_no);
2449        if (unlikely(err)) {
2450            ntfs_error(vol->sb, "Failed to format mft record.");
2451            goto undo_data_init;
2452        }
2453        write_lock_irqsave(&mft_ni->size_lock, flags);
2454        mft_ni->initialized_size = new_initialized_size;
2455    }
2456    write_unlock_irqrestore(&mft_ni->size_lock, flags);
2457    record_formatted = true;
2458    /* Update the mft data attribute record to reflect the new sizes. */
2459    m = map_mft_record(mft_ni);
2460    if (IS_ERR(m)) {
2461        ntfs_error(vol->sb, "Failed to map mft record.");
2462        err = PTR_ERR(m);
2463        goto undo_data_init;
2464    }
2465    ctx = ntfs_attr_get_search_ctx(mft_ni, m);
2466    if (unlikely(!ctx)) {
2467        ntfs_error(vol->sb, "Failed to get search context.");
2468        err = -ENOMEM;
2469        unmap_mft_record(mft_ni);
2470        goto undo_data_init;
2471    }
2472    err = ntfs_attr_lookup(mft_ni->type, mft_ni->name, mft_ni->name_len,
2473            CASE_SENSITIVE, 0, NULL, 0, ctx);
2474    if (unlikely(err)) {
2475        ntfs_error(vol->sb, "Failed to find first attribute extent of "
2476                "mft data attribute.");
2477        ntfs_attr_put_search_ctx(ctx);
2478        unmap_mft_record(mft_ni);
2479        goto undo_data_init;
2480    }
2481    a = ctx->attr;
2482    read_lock_irqsave(&mft_ni->size_lock, flags);
2483    a->data.non_resident.initialized_size =
2484            cpu_to_sle64(mft_ni->initialized_size);
2485    a->data.non_resident.data_size =
2486            cpu_to_sle64(i_size_read(vol->mft_ino));
2487    read_unlock_irqrestore(&mft_ni->size_lock, flags);
2488    /* Ensure the changes make it to disk. */
2489    flush_dcache_mft_record_page(ctx->ntfs_ino);
2490    mark_mft_record_dirty(ctx->ntfs_ino);
2491    ntfs_attr_put_search_ctx(ctx);
2492    unmap_mft_record(mft_ni);
2493    read_lock_irqsave(&mft_ni->size_lock, flags);
2494    ntfs_debug("Status of mft data after mft record initialization: "
2495            "allocated_size 0x%llx, data_size 0x%llx, "
2496            "initialized_size 0x%llx.",
2497            (long long)mft_ni->allocated_size,
2498            (long long)i_size_read(vol->mft_ino),
2499            (long long)mft_ni->initialized_size);
2500    BUG_ON(i_size_read(vol->mft_ino) > mft_ni->allocated_size);
2501    BUG_ON(mft_ni->initialized_size > i_size_read(vol->mft_ino));
2502    read_unlock_irqrestore(&mft_ni->size_lock, flags);
2503mft_rec_already_initialized:
2504    /*
2505     * We can finally drop the mft bitmap lock as the mft data attribute
2506     * has been fully updated. The only disparity left is that the
2507     * allocated mft record still needs to be marked as in use to match the
2508     * set bit in the mft bitmap but this is actually not a problem since
2509     * this mft record is not referenced from anywhere yet and the fact
2510     * that it is allocated in the mft bitmap means that no-one will try to
2511     * allocate it either.
2512     */
2513    up_write(&vol->mftbmp_lock);
2514    /*
2515     * We now have allocated and initialized the mft record. Calculate the
2516     * index of and the offset within the page cache page the record is in.
2517     */
2518    index = bit << vol->mft_record_size_bits >> PAGE_CACHE_SHIFT;
2519    ofs = (bit << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
2520    /* Read, map, and pin the page containing the mft record. */
2521    page = ntfs_map_page(vol->mft_ino->i_mapping, index);
2522    if (IS_ERR(page)) {
2523        ntfs_error(vol->sb, "Failed to map page containing allocated "
2524                "mft record 0x%llx.", (long long)bit);
2525        err = PTR_ERR(page);
2526        goto undo_mftbmp_alloc;
2527    }
2528    lock_page(page);
2529    BUG_ON(!PageUptodate(page));
2530    ClearPageUptodate(page);
2531    m = (MFT_RECORD*)((u8*)page_address(page) + ofs);
2532    /* If we just formatted the mft record no need to do it again. */
2533    if (!record_formatted) {
2534        /* Sanity check that the mft record is really not in use. */
2535        if (ntfs_is_file_record(m->magic) &&
2536                (m->flags & MFT_RECORD_IN_USE)) {
2537            ntfs_error(vol->sb, "Mft record 0x%llx was marked "
2538                    "free in mft bitmap but is marked "
2539                    "used itself. Corrupt filesystem. "
2540                    "Unmount and run chkdsk.",
2541                    (long long)bit);
2542            err = -EIO;
2543            SetPageUptodate(page);
2544            unlock_page(page);
2545            ntfs_unmap_page(page);
2546            NVolSetErrors(vol);
2547            goto undo_mftbmp_alloc;
2548        }
2549        /*
2550         * We need to (re-)format the mft record, preserving the
2551         * sequence number if it is not zero as well as the update
2552         * sequence number if it is not zero or -1 (0xffff). This
2553         * means we do not need to care whether or not something went
2554         * wrong with the previous mft record.
2555         */
2556        seq_no = m->sequence_number;
2557        usn = *(le16*)((u8*)m + le16_to_cpu(m->usa_ofs));
2558        err = ntfs_mft_record_layout(vol, bit, m);
2559        if (unlikely(err)) {
2560            ntfs_error(vol->sb, "Failed to layout allocated mft "
2561                    "record 0x%llx.", (long long)bit);
2562            SetPageUptodate(page);
2563            unlock_page(page);
2564            ntfs_unmap_page(page);
2565            goto undo_mftbmp_alloc;
2566        }
2567        if (seq_no)
2568            m->sequence_number = seq_no;
2569        if (usn && le16_to_cpu(usn) != 0xffff)
2570            *(le16*)((u8*)m + le16_to_cpu(m->usa_ofs)) = usn;
2571    }
2572    /* Set the mft record itself in use. */
2573    m->flags |= MFT_RECORD_IN_USE;
2574    if (S_ISDIR(mode))
2575        m->flags |= MFT_RECORD_IS_DIRECTORY;
2576    flush_dcache_page(page);
2577    SetPageUptodate(page);
2578    if (base_ni) {
2579        MFT_RECORD *m_tmp;
2580
2581        /*
2582         * Setup the base mft record in the extent mft record. This
2583         * completes initialization of the allocated extent mft record
2584         * and we can simply use it with map_extent_mft_record().
2585         */
2586        m->base_mft_record = MK_LE_MREF(base_ni->mft_no,
2587                base_ni->seq_no);
2588        /*
2589         * Allocate an extent inode structure for the new mft record,
2590         * attach it to the base inode @base_ni and map, pin, and lock
2591         * its, i.e. the allocated, mft record.
2592         */
2593        m_tmp = map_extent_mft_record(base_ni, bit, &ni);
2594        if (IS_ERR(m_tmp)) {
2595            ntfs_error(vol->sb, "Failed to map allocated extent "
2596                    "mft record 0x%llx.", (long long)bit);
2597            err = PTR_ERR(m_tmp);
2598            /* Set the mft record itself not in use. */
2599            m->flags &= cpu_to_le16(
2600                    ~le16_to_cpu(MFT_RECORD_IN_USE));
2601            flush_dcache_page(page);
2602            /* Make sure the mft record is written out to disk. */
2603            mark_ntfs_record_dirty(page, ofs);
2604            unlock_page(page);
2605            ntfs_unmap_page(page);
2606            goto undo_mftbmp_alloc;
2607        }
2608        BUG_ON(m != m_tmp);
2609        /*
2610         * Make sure the allocated mft record is written out to disk.
2611         * No need to set the inode dirty because the caller is going
2612         * to do that anyway after finishing with the new extent mft
2613         * record (e.g. at a minimum a new attribute will be added to
2614         * the mft record.
2615         */
2616        mark_ntfs_record_dirty(page, ofs);
2617        unlock_page(page);
2618        /*
2619         * Need to unmap the page since map_extent_mft_record() mapped
2620         * it as well so we have it mapped twice at the moment.
2621         */
2622        ntfs_unmap_page(page);
2623    } else {
2624        /*
2625         * Allocate a new VFS inode and set it up. NOTE: @vi->i_nlink
2626         * is set to 1 but the mft record->link_count is 0. The caller
2627         * needs to bear this in mind.
2628         */
2629        vi = new_inode(vol->sb);
2630        if (unlikely(!vi)) {
2631            err = -ENOMEM;
2632            /* Set the mft record itself not in use. */
2633            m->flags &= cpu_to_le16(
2634                    ~le16_to_cpu(MFT_RECORD_IN_USE));
2635            flush_dcache_page(page);
2636            /* Make sure the mft record is written out to disk. */
2637            mark_ntfs_record_dirty(page, ofs);
2638            unlock_page(page);
2639            ntfs_unmap_page(page);
2640            goto undo_mftbmp_alloc;
2641        }
2642        vi->i_ino = bit;
2643        /*
2644         * This is for checking whether an inode has changed w.r.t. a
2645         * file so that the file can be updated if necessary (compare
2646         * with f_version).
2647         */
2648        vi->i_version = 1;
2649
2650        /* The owner and group come from the ntfs volume. */
2651        vi->i_uid = vol->uid;
2652        vi->i_gid = vol->gid;
2653
2654        /* Initialize the ntfs specific part of @vi. */
2655        ntfs_init_big_inode(vi);
2656        ni = NTFS_I(vi);
2657        /*
2658         * Set the appropriate mode, attribute type, and name. For
2659         * directories, also setup the index values to the defaults.
2660         */
2661        if (S_ISDIR(mode)) {
2662            vi->i_mode = S_IFDIR | S_IRWXUGO;
2663            vi->i_mode &= ~vol->dmask;
2664
2665            NInoSetMstProtected(ni);
2666            ni->type = AT_INDEX_ALLOCATION;
2667            ni->name = I30;
2668            ni->name_len = 4;
2669
2670            ni->itype.index.block_size = 4096;
2671            ni->itype.index.block_size_bits = ntfs_ffs(4096) - 1;
2672            ni->itype.index.collation_rule = COLLATION_FILE_NAME;
2673            if (vol->cluster_size <= ni->itype.index.block_size) {
2674                ni->itype.index.vcn_size = vol->cluster_size;
2675                ni->itype.index.vcn_size_bits =
2676                        vol->cluster_size_bits;
2677            } else {
2678                ni->itype.index.vcn_size = vol->sector_size;
2679                ni->itype.index.vcn_size_bits =
2680                        vol->sector_size_bits;
2681            }
2682        } else {
2683            vi->i_mode = S_IFREG | S_IRWXUGO;
2684            vi->i_mode &= ~vol->fmask;
2685
2686            ni->type = AT_DATA;
2687            ni->name = NULL;
2688            ni->name_len = 0;
2689        }
2690        if (IS_RDONLY(vi))
2691            vi->i_mode &= ~S_IWUGO;
2692
2693        /* Set the inode times to the current time. */
2694        vi->i_atime = vi->i_mtime = vi->i_ctime =
2695            current_fs_time(vi->i_sb);
2696        /*
2697         * Set the file size to 0, the ntfs inode sizes are set to 0 by
2698         * the call to ntfs_init_big_inode() below.
2699         */
2700        vi->i_size = 0;
2701        vi->i_blocks = 0;
2702
2703        /* Set the sequence number. */
2704        vi->i_generation = ni->seq_no = le16_to_cpu(m->sequence_number);
2705        /*
2706         * Manually map, pin, and lock the mft record as we already
2707         * have its page mapped and it is very easy to do.
2708         */
2709        atomic_inc(&ni->count);
2710        mutex_lock(&ni->mrec_lock);
2711        ni->page = page;
2712        ni->page_ofs = ofs;
2713        /*
2714         * Make sure the allocated mft record is written out to disk.
2715         * NOTE: We do not set the ntfs inode dirty because this would
2716         * fail in ntfs_write_inode() because the inode does not have a
2717         * standard information attribute yet. Also, there is no need
2718         * to set the inode dirty because the caller is going to do
2719         * that anyway after finishing with the new mft record (e.g. at
2720         * a minimum some new attributes will be added to the mft
2721         * record.
2722         */
2723        mark_ntfs_record_dirty(page, ofs);
2724        unlock_page(page);
2725
2726        /* Add the inode to the inode hash for the superblock. */
2727        insert_inode_hash(vi);
2728
2729        /* Update the default mft allocation position. */
2730        vol->mft_data_pos = bit + 1;
2731    }
2732    /*
2733     * Return the opened, allocated inode of the allocated mft record as
2734     * well as the mapped, pinned, and locked mft record.
2735     */
2736    ntfs_debug("Returning opened, allocated %sinode 0x%llx.",
2737            base_ni ? "extent " : "", (long long)bit);
2738    *mrec = m;
2739    return ni;
2740undo_data_init:
2741    write_lock_irqsave(&mft_ni->size_lock, flags);
2742    mft_ni->initialized_size = old_data_initialized;
2743    i_size_write(vol->mft_ino, old_data_size);
2744    write_unlock_irqrestore(&mft_ni->size_lock, flags);
2745    goto undo_mftbmp_alloc_nolock;
2746undo_mftbmp_alloc:
2747    down_write(&vol->mftbmp_lock);
2748undo_mftbmp_alloc_nolock:
2749    if (ntfs_bitmap_clear_bit(vol->mftbmp_ino, bit)) {
2750        ntfs_error(vol->sb, "Failed to clear bit in mft bitmap.%s", es);
2751        NVolSetErrors(vol);
2752    }
2753    up_write(&vol->mftbmp_lock);
2754err_out:
2755    return ERR_PTR(err);
2756max_err_out:
2757    ntfs_warning(vol->sb, "Cannot allocate mft record because the maximum "
2758            "number of inodes (2^32) has already been reached.");
2759    up_write(&vol->mftbmp_lock);
2760    return ERR_PTR(-ENOSPC);
2761}
2762
2763/**
2764 * ntfs_extent_mft_record_free - free an extent mft record on an ntfs volume
2765 * @ni: ntfs inode of the mapped extent mft record to free
2766 * @m: mapped extent mft record of the ntfs inode @ni
2767 *
2768 * Free the mapped extent mft record @m of the extent ntfs inode @ni.
2769 *
2770 * Note that this function unmaps the mft record and closes and destroys @ni
2771 * internally and hence you cannot use either @ni nor @m any more after this
2772 * function returns success.
2773 *
2774 * On success return 0 and on error return -errno. @ni and @m are still valid
2775 * in this case and have not been freed.
2776 *
2777 * For some errors an error message is displayed and the success code 0 is
2778 * returned and the volume is then left dirty on umount. This makes sense in
2779 * case we could not rollback the changes that were already done since the
2780 * caller no longer wants to reference this mft record so it does not matter to
2781 * the caller if something is wrong with it as long as it is properly detached
2782 * from the base inode.
2783 */
2784int ntfs_extent_mft_record_free(ntfs_inode *ni, MFT_RECORD *m)
2785{
2786    unsigned long mft_no = ni->mft_no;
2787    ntfs_volume *vol = ni->vol;
2788    ntfs_inode *base_ni;
2789    ntfs_inode **extent_nis;
2790    int i, err;
2791    le16 old_seq_no;
2792    u16 seq_no;
2793    
2794    BUG_ON(NInoAttr(ni));
2795    BUG_ON(ni->nr_extents != -1);
2796
2797    mutex_lock(&ni->extent_lock);
2798    base_ni = ni->ext.base_ntfs_ino;
2799    mutex_unlock(&ni->extent_lock);
2800
2801    BUG_ON(base_ni->nr_extents <= 0);
2802
2803    ntfs_debug("Entering for extent inode 0x%lx, base inode 0x%lx.\n",
2804            mft_no, base_ni->mft_no);
2805
2806    mutex_lock(&base_ni->extent_lock);
2807
2808    /* Make sure we are holding the only reference to the extent inode. */
2809    if (atomic_read(&ni->count) > 2) {
2810        ntfs_error(vol->sb, "Tried to free busy extent inode 0x%lx, "
2811                "not freeing.", base_ni->mft_no);
2812        mutex_unlock(&base_ni->extent_lock);
2813        return -EBUSY;
2814    }
2815
2816    /* Dissociate the ntfs inode from the base inode. */
2817    extent_nis = base_ni->ext.extent_ntfs_inos;
2818    err = -ENOENT;
2819    for (i = 0; i < base_ni->nr_extents; i++) {
2820        if (ni != extent_nis[i])
2821            continue;
2822        extent_nis += i;
2823        base_ni->nr_extents--;
2824        memmove(extent_nis, extent_nis + 1, (base_ni->nr_extents - i) *
2825                sizeof(ntfs_inode*));
2826        err = 0;
2827        break;
2828    }
2829
2830    mutex_unlock(&base_ni->extent_lock);
2831
2832    if (unlikely(err)) {
2833        ntfs_error(vol->sb, "Extent inode 0x%lx is not attached to "
2834                "its base inode 0x%lx.", mft_no,
2835                base_ni->mft_no);
2836        BUG();
2837    }
2838
2839    /*
2840     * The extent inode is no longer attached to the base inode so no one
2841     * can get a reference to it any more.
2842     */
2843
2844    /* Mark the mft record as not in use. */
2845    m->flags &= ~MFT_RECORD_IN_USE;
2846
2847    /* Increment the sequence number, skipping zero, if it is not zero. */
2848    old_seq_no = m->sequence_number;
2849    seq_no = le16_to_cpu(old_seq_no);
2850    if (seq_no == 0xffff)
2851        seq_no = 1;
2852    else if (seq_no)
2853        seq_no++;
2854    m->sequence_number = cpu_to_le16(seq_no);
2855
2856    /*
2857     * Set the ntfs inode dirty and write it out. We do not need to worry
2858     * about the base inode here since whatever caused the extent mft
2859     * record to be freed is guaranteed to do it already.
2860     */
2861    NInoSetDirty(ni);
2862    err = write_mft_record(ni, m, 0);
2863    if (unlikely(err)) {
2864        ntfs_error(vol->sb, "Failed to write mft record 0x%lx, not "
2865                "freeing.", mft_no);
2866        goto rollback;
2867    }
2868rollback_error:
2869    /* Unmap and throw away the now freed extent inode. */
2870    unmap_extent_mft_record(ni);
2871    ntfs_clear_extent_inode(ni);
2872
2873    /* Clear the bit in the $MFT/$BITMAP corresponding to this record. */
2874    down_write(&vol->mftbmp_lock);
2875    err = ntfs_bitmap_clear_bit(vol->mftbmp_ino, mft_no);
2876    up_write(&vol->mftbmp_lock);
2877    if (unlikely(err)) {
2878        /*
2879         * The extent inode is gone but we failed to deallocate it in
2880         * the mft bitmap. Just emit a warning and leave the volume
2881         * dirty on umount.
2882         */
2883        ntfs_error(vol->sb, "Failed to clear bit in mft bitmap.%s", es);
2884        NVolSetErrors(vol);
2885    }
2886    return 0;
2887rollback:
2888    /* Rollback what we did... */
2889    mutex_lock(&base_ni->extent_lock);
2890    extent_nis = base_ni->ext.extent_ntfs_inos;
2891    if (!(base_ni->nr_extents & 3)) {
2892        int new_size = (base_ni->nr_extents + 4) * sizeof(ntfs_inode*);
2893
2894        extent_nis = kmalloc(new_size, GFP_NOFS);
2895        if (unlikely(!extent_nis)) {
2896            ntfs_error(vol->sb, "Failed to allocate internal "
2897                    "buffer during rollback.%s", es);
2898            mutex_unlock(&base_ni->extent_lock);
2899            NVolSetErrors(vol);
2900            goto rollback_error;
2901        }
2902        if (base_ni->nr_extents) {
2903            BUG_ON(!base_ni->ext.extent_ntfs_inos);
2904            memcpy(extent_nis, base_ni->ext.extent_ntfs_inos,
2905                    new_size - 4 * sizeof(ntfs_inode*));
2906            kfree(base_ni->ext.extent_ntfs_inos);
2907        }
2908        base_ni->ext.extent_ntfs_inos = extent_nis;
2909    }
2910    m->flags |= MFT_RECORD_IN_USE;
2911    m->sequence_number = old_seq_no;
2912    extent_nis[base_ni->nr_extents++] = ni;
2913    mutex_unlock(&base_ni->extent_lock);
2914    mark_mft_record_dirty(ni);
2915    return err;
2916}
2917#endif /* NTFS_RW */
2918

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